WARTIME AIR DEFENCES IN PANAMA

WARTIME AIR DEFENCES IN PANAMA

As discussed previously, air defences of the Panama Canal Zone in the late 1930s were recognised as being insufficient, and that defences were of necessity concentrated in the territory of the narrow Zone, for most of its length just 10 miles wide, seemingly leaving the remainder of the Republic of Panama open to being used as a route or base for any attacker.

Furthermore, a 1939 project had concluded that Canal installations were vulnerable should an aerial attack be mounted, the outcome of the project being forwarded to the US War Department in March 1939, with the commander of the resident 19th Wing urging a reorganisation of the air defences.[1]

As early as 1929, Summer manoeuvres had demonstrated the superiority of a carrier attack force over land-based defences when, despite the defenders knowing the day of the planned mock attack and having as many aircraft as the attacking fleet, the “enemy” was able to come within 150 miles of the Pacific end of the Canal before launching its attacking aircraft bombers in the predawn darkness and were over the Canal by the time that the defenders knew it was coming.  However, senior Army leaders responded that the Navy’s conduct in the manoeuvres and the propaganda that followed it was further evidence of an intention to belittle the Army and take from the Army the role of defending the US coasts.

In 1930, the Secretary of War had asked for recommendations for improvements of the US Army Air Corps’ (USAAC) 5-year programme.  The USAAC response was that the minimum air force “capable of discouraging hostile attack” on the Continental US, Panama, and Hawaii would involve 3,100 aircraft.  This was some 1,300 more than the planned goal of the 5-year plan.  Furthermore, it said, still more would be needed if the Philippine Islands were also to have adequate air defences.  The cost of acquiring these 3,100 aircraft over the four years available would have been approximately $62 million annually.  Given that the US was entering into what we now know as the Great Depression, this was unrealistic, to say the least.  However, it was agreed that the 1,800 serviceable aircraft authorised in the 5-year programme would include only those aircraft available for active duty[2].

The US Navy had estimated what size bomb, exploding in a filled lock, could damage or destroy the lock plates sufficient to put the gate out of commission.  The problem, as evidence in attacks on dock and lock gates, and the German dams on the Ruhr, during World War 2 was being to accurately place the requisite amount of high explosives is just the right place to cause the maximum (or any real) damage.  More vulnerable, though perhaps more easily repaired, were the associated installations, control centres, power stations etc.  Nevertheless, the aforementioned 1939 study, which used a replica of one level of the Miraflores Locks, concluded that a relatively small force was required (being well within the capabilities of several foreign powers).[3]

As previously mentioned, at the end of Fiscal Year 1938, the Secretary of War, in a report to the President, had stated that – “We must greatly augment our air forces and our antiaircraft artillery installations in the Panama Canal Zone.  The Panama Canal must be made impregnable”.[4]  However, this remained to be far from the case in the period leading up the US entry into the war, and in all likelihood for some time thereafter – air defences were described as inadequate as late as 1940-41.  However, in 1939, after hurried arrangements were made with Mexico and the Central American Republics for overflights, 30 new P-36 Hawk fighters were flown down to reinforce the air garrison and replace the obsolete types in use[5]

While sabotage remained seen as being a major threat (leading, for example, to armed guards being placed on ships in transit through the Canal), in the 1930s an air attack by either land-based or carrier-based planes came to be regarded as a more serious threat because of the gaps in the defence against them.

Given the higher threat level given to air attacks, under the new war planning adopted in 1939 it became US policy to prevent the development of any potentially hostile airbases on land that could threaten the Canal – either to attack the Canal itself, or to support a surface attack or landings.  This threat was not an entirely notional, given German influence and presence in parts of South America.

Local defence plans gave the USAAC the responsibility of air defence of the Canal, with the understanding that naval patrol aircraft would carry out distant reconnaissance, patrolling, reporting, and tracking.  The two major tasks of the USAAC consisted of furnishing an offensive or striking force to destroy enemy vessels encountered and of furnishing a defensive force to combat air attacks.  Similar missions were assumed by other USAAC contingents as bases were established throughout the Caribbean and by the Caribbean Air Force command when it was activated in May 1941.  In the following, I am going to concentrate on the air defences, but excluding any actual fighters[6] employed in air defence.

GUNS

Prior to the outbreak of World War 2 in 1939 there had been limited anti-aircraft defences in the Canal Zone, comprising 12 3-inch (76.2 mm) gun batteries for engaging high-level bombers[7], 37 mm cannon[8] and 0.5-inch machine guns[9] for defence against low-flying aircraft[10], and searchlights.  In June 1940, all anti-aircraft defences were ordered to wartime status, and remained at this level of preparedness until 1945. 

The 3-inch gun was found to have limited effectiveness against high-speed, high-altitude aircraft and thus were clustered close to targets, for use against targets at lower altitudes, such as torpedo bombers and dive bombers.  In addition, in December 1941, there was a shortage of ammunition, which hampered and limited training and target practice.

The equipment was to be upgraded as the war progressed, with automatic cannon and additional heavy weapons added – and by December 1942, all the 37 mm guns had been replaced by new 40 mm Bofors guns.  There would also be mobile 3-inch (76.2mm) guns, alongside fixed 3-inch and 105 mm guns, forming an interior defence ring around defended areas.  In July 1944, the Coastal Artillery Command ordered surveys for possible sites for the new 120 mm (4.7-inch) guns[11], and by December 1944, Battery 80 at Camp Chiva and Battery 81 near the Empire Range had been approved.  Eventually, about 15 M1 120 mm guns were sent to the Canal Zone[12].  However, none was ever fired against an enemy (manned) aircraft anywhere during the war and only about 550 M1 were produced.

From 1941, a plan allowed the gun batteries to provide supporting fire to the Mobile Force, as well as serving a secondary harbour defence role in the Atlantic sector.  Then, in February 1942, instructions were received from Coast Artillery Command to establish a system of barrage fire, the first involving a fixed barrage at 500 feet (152 metres) above the Pedro Miguel and Miraflores Locks.  The barrage was seen as an alternative until the development of a radar-controlled barrage.

The actual anti-aircraft defenses were very weak due to demands for guns in the European conflict.  Only 8 3-inch guns were mounted by 1918.  7 of these guns were in fixed mounts around the seacoast defenses and one gun was mounted on a railway car.  4 more guns were received in late 1918 and were emplaced around the Gatun Dam.  In April 1920, 36 3-inch guns were allocated to the Canal Zone, By 1931, the US Army had emplaced the 3-inch anti-aircraft in 15 3-gun batteries on fixed mounts (throughout the Canal Zone) and one 3-inch battery on railway cars. Supporting these anti-aircraft guns were 29 mobile 60-inch searchlights and 16 0.50-calibre machine guns.”[13]

The American Defenses of the Panama Canal by Terrance McGovern (1999)

The attack on Pearl Harbor had demonstrated that the Coast Artillery, despite the inclusion of the anti-aircraft mission, could be largely ineffective against a mass air attack.  Pre-war anti-aircraft planning had been very inadequate.  In addition, the artillery deployed for coastal defence had become almost irrelevant, the guns being positioned to deter enemy warships.  In the Philippines, for example, the coastal artillery had proved vulnerable to both air and high-angle artillery attack [14]

The US Congress had approved a total of $50 million in funding for improving the defences of the Canal in 1939, and funds became available from July 1939, and the bulk of the programme was to be completed by early 1942, an exception being outposts, including airfields, outside the Canal Zone (which had to wait until the successful conclusion of a bases agreement with the Panamanian Government in 1942).

During 1939 and the first months of 1940, US Army engineers began the task of improving the defences of the Canal Zone[15], but it was considered essential that some of the 153 searchlights and most of the aircraft warning stations[16] required would have to be located outside the Canal Zone to be effective,[17] and hence the need for the additional bases in the Republic for which negotiations were to drag on into 1942.

In September 1939, the 73rd Coast Artillery Regiment, the only anti-aircraft regiment in the Panama Canal Department had been activated, and on 20 June 1940, all anti-aircraft units were ordered to their war stations and remained so activated for the duration of the war.

Prior to October 1939, the Antiaircraft Defense Board of the Panama Canal Department made all decisions on anti-aircraft defences . Then, on 20 November 1940, the Panama Coast Artillery Command was formed comprising two anti-aircraft brigades, alongside the Harbor Defense units at either end of the Canal –

  • 76th Antiaircraft Artillery Brigade – for air defence of the Pacific Canal sector, including the Pedro Miguel Locks; Miraflores Locks; Spillway and power plants; Madden Dam; Albrook Field and Howard Field airbases; and the Navy facilities at Balboa Dry Dock and tank farm; and
  • 75th Antiaircraft Artillery Brigade – for air defence of the Atlantic sector, including the Gatun Locks, Dam and Spillway; Mount Hope Filtration Plant; France Field airbase; and Coco Solo, with its submarine base and air station.

During the war annual anti-aircraft and automatic weapons firing exercises were held at the Rio Hato Gunnery Camp, about 75 miles (120 km) from Panama City on the Pacific coast.  Heavy supplies had to be transported by sea and offloaded onto the beach at Rio Hato until, in 1942, the US Corps of Engineers built a highway from Chorrera out to Rio Hato[18].

One of the precautions considered at the start of the war as for demolishing buildings in the townsites at Red Tank, Paraiso and Pedro Miguel, as the light from burning buildings could illuminate the adjacent locks, and thus aid enemy attackers.  However, a metal fence was installed instead, shading the Canal and locks from any possible illumination.

In 1940, a review had shown there to be a shortage of searchlights, and included a recommendation that those available should be sited on would be the best avenues of approach to the Canal for an attacking aircraft, for the better illumination of any targets.  However, there were difficulties in using the best sites, due to the surrounding jungle terrain and a lack of suitable positions in Panama Bay (resulting in a greater grouping along the shoreline as a result).  During daylight hours searchlights were to be concealed.  Sound locaters were initially sited alongside the searchlights and, later, 0.50-inch (12.7 mm) heavy machine guns were also used for local protection of each light. 

By 1940, there were 11 gun batteries and 32 searchlight positions in the Pacific Sector and, as of 1 October 1939, there were 12 fixed anti-aircraft batteries and what was described as a “few” searchlights in the Atlantic sector.  As an example of later deployment, until September 1943 there were as many as 85 searchlight positions in the Pacific sector.  This was then reduced, in a general reduction in defence levels as percieved threat levels themselves reduced, to just four sites, with 12 searchlights each, as the Pacific Searchlight Defense.

I do not intend to discuss here the introduction of radar in Panama, except to note that,  in February 1942, British radar experts visited and advised on its siting and conversion for use against low-flying aircraft, with the siting of radar units on high hills contributing to the ground clutter which affected readings.  Tests in March 1942 found that the maximum range of the SCR-268 sets against low-flying aircraft was 3,000 to 5,300 yards (2,743 to 4,846 metres), after which the target was lost in ground clutter[19]

Aside from anti-aircraft guns and barrage balloons, amongst the other defences suggested for the Canal Zone were camouflage nets and the creation of dummy locks to deceive an air attacker.  Neither proved feasible. 

BARRAGE BALLOONS

Barrage balloons were also to be employed, some from barges on the Canal itself.  However, by mid-1941 there were still no barrage balloons in place, as well there being a shortage of personnel for the anti-aircraft units and even insufficient ammunition for the 37 mm anti-aircraft guns[20]

Until the start of the war in Europe, the USAAC had received little support for the use of barrage balloons for defence against hostile aircraft.  This was despite the French, British, and Germans having used barrage balloons during World War 1 and Army General Staff, when it undertook studies of anti-aircraft defences in the early 192Os, having advocated balloons as an effective and relatively inexpensive defence for the Panama Canal, the Capitol in Washington, the White House, and important dry docks, wharves, factories, and bridges in the US. 

Responsibility for barrage balloons was divided between the USAAC – for developing equipment – and the Coast Artillery – for actual deployment and use.  Development between the two world wars was slow and suffered from both a lack of funding and a widespread lack of enthusiasm for the programme.  Only minor developments occurred between 1923 and 1939, and the inter-service rivalry between the USAAC and the Coast Artillery Corps[21].  Nevertheless, the War Department included barrage balloons in defence plans – the anti-aircraft defences of the Panama Canal, for instance, called for 74 balloons in two barrages, one at either end of the Canal. 

Matters reached a state that, in 1937, a meeting organised by the Army saw the Coastal Artillery making the point that it thought that funds could be better used for active anti-aircraft projects, with the War Department General Staff expressed the same opinion, leaving only the USAAC representatives in favour of barrage balloon experiments,  and continuing its work although only $5,000 in funding was available[22].  The balloon barrage was also dropped from plans for defence of the Canal, but after the British and French undertook sizable barrage balloon programmes in 1937, the USAAC decided to use the $5,000 of its own funds to buy a single balloon for experiments.  In 1939, this sole balloon was sent to Panama to obtain data on deterioration in storage – but it took the war in Europe to spur the War Department into further development of barrage balloons.[23]

Finally, in Summer 1940, the USAAC was able to make $50,000 available for barrage balloon equipment and in June 1940, Goodyear-Zeppelin was awarded a contract for the first low-altitude balloons, for delivery in 1941[24].  A study undertaken in 1940 had recommended acquiring no less than 4,400 barrage balloons, including 200 for deployment in Panama[25], with an estimate of production rates being that 5,310 balloons could be produced by January 1943[26].  By 1942, the Canal Zone was second in priority for barrage balloons only to the Soo locks and canal between Lake Superior and the lower Great Lakes, which also saw much-enhanced anti-aircraft gun defences.

The Japanese attack on Pearl Harbor had brought the barrage balloon programme to the forefront of attention.  Consequently, on 1 January 1942, the 301st Coast Artillery Battalion (Separate Barrage Balloon) arrived in the Canal Zone, being composed of troops from the Barrage Balloon School, and which had been the first such battalion formed, and began operating at the Pacific end of the Canal[27].  Already the US Marines Corp 1st Barrage Balloon Squadron (designated ZMQ-l by the US Navy) had arrived at Fort Randolph on 30 December.  Formally attached to the 15th Naval District, it was assigned to the Army command.  It was not until September 1942 that the Marines unit could be replaced by the new 313th Coastal Artillery Barrage Balloon Battalion (formed from a cadre of the 301st Battalion)[28], allowing AMQ-1 to return to the US.  

At the Pacific end of the Canal 36 sites were planned, and all were operational in May 1942, 20 at Pedro Miguel and 16 at Miraflores Locks.  By June, there were two rings of balloons around the locks and a line of balloons on either side of the Canal between the two sets of locks.  Latterly, there would be a total of 56 balloons in use.  The balloons were sited 300 yards (274 metres) apart and could protect against a dive bombing attack from 5,000 feet (1,524 mtres) at a 60° dive angle.

One problem faced initially was the shortage of the necessary hydrogen or helium in Panama[29].  Other problems were found with the high winds during the dry season, as well from a shortage of balloons and with defective examples.  The winches first used were also found to be unsatisfactory, with cables breaking at about 4,000 lb (1,814 kg) pull.  The balloons had to be painted with aluminium paint to reflect the heat and improve life of the fabric.  Then, in June 1943, several balloon positions had to be abandoned due to poor road contitions (it being the wet season) and repairs could not be undertaken due to the impending reduction in troop numbers – and by July 1943, there were only 30 balloons in service, due to resupply problems.

In December 1943, as part of the general reduction in strength of the Panama Canal Department, all barrage balloon positions were abandoned and the units returned to the US for reassignment.[30]

SMOKESCREENS

Another suggestion that was taken up was to lay down a smokescreen.  This had been first considered in 1930, but it was not until 1942 that smoke generators were ordered into place to protect certain installations.  Thousands of “smoke pot” smoke generators were employed, including on barges in the Canal itself.  Interestingly, the smoke defence units, though Coast Artillery units, came under the operational control of the USAAC (later USAAF) Interceptor Command[31].

The smoke screen defences were first tested by the Army’s Chemical Warfare Service (CWS) at the Pedro Miguel Locks in February 1942, and this revealed that an effective screen could be laid down in 30 minutes, using M1 oil-powered smoke generators.  Shortly after the Pearl Harbor attack, the CWS deployed stationary 100-gallon M1 oil generators to protect the Canal, locks and other important industrial sites.  These were similar to smudge pots, generating clouds of dense oily smoke.  Because of the weight and size of the M1, they were only deployed at fixed points surrounding the Canal[32].  In March 1942, the Coast Artillery Command directed that smoke generators be installed immediately and, by the end of the month, the Miraflores and Pedro Miguel installations were complete.  The Pedro Miguel smokescreen was tested in April, and the first smoke barges were installed at Miraflores Locks that month. 

By January 1943, 27 barges were manned and in use to provide a smokescreen and, in total, 5,990 smoke generators were employed in the Gatun area, 3,138 at Pedro Miguel, 3,906 at Miraflores Locks and 12 at the Madden Dam.  The Gatun area included 67 barges, many of which were also used to control barrage balloons.

However, effectiveness of the smokescreen (and the complicating side-effects it could cause – it was found to interfere with the automatic weapons, and did not deter high-flying bombers) was queried and the original ambitious plan to provide widespread smokescreen protection was to be cut back, and provided only for the locks and dams.  Even so, in late 1943, as perceived threats diminished, use of both the smokescreen and barrage balloons were reduced[33] and, in August 1943, use of the smokescreen was discontinued during daylight, only the Madden Dam generators were manned on full alert, that is both day and night.[34]  From October 1943, the equipment was physically removed to store and its use was officially terminated on 1 December 1943 as troop levels were being reduced.  Almost 900 men (plus 200 boats and barges) had been necessary to provide the smokescreen defence.

THE KILLER CURTAIN

Another aerial defence system installed in 1942 was the so-called “killer curtain”, an aerial cable draw net situated near the Pedro Miguel Locks, and designed to deter low-flying torpedo-bombers.  It was normally only raised into position during an alert, this taking around five minutes.  It was deployed between two hills – Cerro Luisa and Cerro Paraiso[35]  600 feet (183 metres) from the north end of the centre wall of the Pedro Miguel Locks.  The main cable was suspended 250 feet (76.2 metres) above the Canal, with vertical cables hanging down to water level, and it was operated by the Army’s 301st Barrage Battalion and was always left in place during an alert.

However, its only victim was a USAAF North American O-47 observation aircraft, which hit it in 1943, resulting in the falling curtain falling across the 44,000 volt transmission line for the Panama Railroad, disrupting the power systems and blocking traffic.[36]  Hence, as it had proved to be more of a liability than a benefit, this form of defence was subsequently discarded.

BLACKOUTS AND AIR RAID PRECAUTIONS

Practice air raid alert procedures took place from 1939 until war actually reached the Canal Zone in 1941.  The Governor was responsible for training civilian personel and a director of Civil Defense was appointed, but no firm plans had been made by the time of the Pearl Harbor attack, and the lack of air raid shelters was also seen as a serious problem.  The Canal Zone fire department was augmented by an additional 30 trailer pumps and separate volunteer fire companies were organised to use them[37].

Information was circulated in Civil Defense Bulletins, and the first was issued on 12 December 1941, with the first Warden Bulletin on 18 December – 20 editions eventually being published by July 1945.

From 19 May 1942, a new alert system was introduced, with revised alert and blackout instructions –

  • A normal blackout had lights shielded from 2300 to 0545 (1830 to 0545 from 7 December 1941)[38];
  • An “alert” blackout would be ordered when an attack was imminent, with all lights shielded in the hours of darkness; and
  • A complete blackout was to be in place when the siren sounded, with all outside lights extinguished and all inside lights shields or put out.

Due to non-compliance during practice alerts, from 1 September 1942 the Canal Zone Police were authorised to arrest offenders.

On 21 August 1944, the Commanding General issued new instructions, with unrestricted lighting allowed during normal periods of alert, but during a “complete” blackout no lights should be visible, although the power was not turned off and it was for individuals to ensure that lights were shielded or extinguished.

Experiments led to shades being fitted to the essential navigation lights along the Canal which made them invisible to aircraft above 700 feet (213 metres).

Ray Todd

Panamá City

Republic of Panamá

21 August 2022


[1]  Air Defense of the Panama Canal, 1 January 1939 – 7 December 1941 (Army Air Forces Historical Office), January 1946: https://www.afhra.af.mil/Portals/16/documents/Studies/1-50/AFD-090602-096.pdf

[2]  https://www.airuniversity.af.edu/Portals/10/AUPress/Books/B_0062_TATE_ARMY_AIR_CORPS.pd

[3]  Air Defense of the Panama Canal, 1 January 1939 – 7 December 1941 (Army Air Forces Historical Office), January 1946: https://www.afhra.af.mil/Portals/16/documents/Studies/1-50/AFD-090602-096.pdf

[4]  Ibid.

[5]  https://www.ibiblio.org/hyperwar/USA/USA-WH-Guard/USA-WH-Guard-12.html

[6]  Or “pursuit” aircraft, as the USAAC termed fighters, when it became the US Army Air Force in 1941 it would switch to describing them as fighters.

[7]  The standard US Army anti-aircraft gun from 1927, by World War 2 it lacked both the range (it had a slant range of 15,000 feet or 4,572 metres) or the fire control mechanisms needed to track accurately those flying at the greater speeds of the more modern aircraft.  It also only used a light, 12.8 lb (5.8 kg) projectile: (Security and Defense of the Panama Canal 1903-2000 by Charles Morris, Panama Canal Commission).

[8]  The M1 37 mm gun could fire up to 90 rounds per minute, to a range of 10,500 feet (3,200 metres).  Finally adopted, after a long period of testing, in 1939, it became the US Army’s main anti-aircraft gun for the first years of World War 2, being replaced from 1943 by the 40 mm Bofors.   

[9]  The Coast Artillery Command preferred the water-cooled version of the 0.50-inch, the basic M2 model equipped with an outer water-filled jacket and a water pump for cooling the barrel.  However, because a water supply might be hard to maintain under some combat conditions, an air-cooled heavy-barrel model was also designed for ground use where long bursts of fire might be necessary.  The M2 heavy machine gun remains in production, and in US Army use, to this day.  Large numbers of water-cooled M2 also remained the US Navy’s standard short-range anti-aircraft weapon until 1942, when it was realised that they lacked hitting power at typical naval engagement rages; they were gradually replaced by 20 mm Oerlikon cannon.

[10]   Initially without the requested sights and tracer ammunition – and the 37 mm guns also suffered from a shortage of ammunition.

[11]  After a long gestation, the 120 mm AA Gun M1 was standardised in 1944.

[12]  Some were also sent to Britain, to bolster defences against the V-1.

[13]  The American Defenses of the Panama Canal by Terrance McGovern (1999) via http://www.czimages.com/CZMemories/Photos/photoof854.htm

[14] https://www.wikiwand.com/en/United_States_Army_Coast_Artillery_Corps

[15]  https://history.army.mil/html/books/010/10-6/CMH_Pub_10-6.pdf

[16]  Until radar was available, these would rely on sound locaters and eyesight.

[17]  https://history.army.mil/html/books/010/10-6/CMH_Pub_10-6.pdf

[18]  This now forms part of the Pan-American Highway.

[19]  The later SCR-545 sets received in April 1944 suffered from the same ground clutter problem, albeit to a lesser degree.  They too were unable to detect targets over land and below 1,000 feet (305 metres) altitude. 

[20]  It is said that the 37 mm guns had only enough shells for 1 minute’s firing: https://www.ibiblio.org/hyperwar/USA/USA-WH-Guard/USA-WH-Guard-13.html

[21]  https://xbradtc2.com/tag/coastal-artillery/

[22]  The US Army Barrage Balloon Program by James R. Shock (Marriam Press), 2006.

[23]  Aviation in the US. Army, 1919-1939 by Maurer Maurer, (United States Air Force Historical Research Center (Office of Air Force History), 1987.

[24]  The US Army Barrage Balloon Program by James R. Shock (Marriam Press), 2006

[25]  It was estimated that around 2,400 men would be required to operate 90 balloons in the Gatun Lake area and 110 balloons in the area of the Pedro Miguel and Miraflores Locks.

[26]  Ibid.

[27]  The US Army Barrage Balloon Program by James R. Shock (Marriam Press), 2006.

[28]  Ibid.

[29]  80,000 cylinders of helium had arrived with the first balloon unit (enough for 50 balloons).  However, hydrogen would be produced in the Canal Zone, producing about 1 million cubic feet a month, and an experimental field plant, capable of producing about 60,000 cubic feet a day, had been brought to Panama as well and was used in the Atlantic sector.

[30]  Security and Defense of the Panama Canal 1903-2000 by Charles Morris, Panama Canal Commission: https://original-ufdc.uflib.ufl.edu/AA00047733/00001/6j

[31]  Security and Defense of the Panama Canal 1903-2000 by Charles Morris, Panama Canal Commission: https://original-ufdc.uflib.ufl.edu/AA00047733/00001/6j

[32]  Smoke Operations in 21st Century Warfare by Al Mauroni (Association of the United States Army), April 1997: https://www.ausa.org/sites/default/files/LPE-97-2-Smoke-Operations-in-21st-Century-Warfare.pdf

[33]  https://apps.dtic.mil/dtic/tr/fulltext/u2/a388262.pdf

[34]  However, a 1954 movie produced by the US Army about the defences of the Canal showed such smoke pots being used to obscure the Canal.

[35]  Cerro Luisa is on the east bank, overlooking the town of Pedro Miguel, and Cerro Paraiso opposite it on the west bank.

[36]  Security and Defense of the Panama Canal 1903-2000 by Charles Morris, Panama Canal Commission: https://original-ufdc.uflib.ufl.edu/AA00047733/00001/6j The pilot, 2nd Lieutenant Walter Weatherly USAAF, was killed, but the other crewman survived and was rescued.

[37]  Security and Defense of the Panama Canal 1903-2000 by Charles Morris, Panama Canal Commission: https://original-ufdc.uflib.ufl.edu/AA00047733/00001/6j

[38]  As now, being so near the equator, year-round there are around 12 hours daylight: 0600 to 1800.

Author: raytodd2017

Chartered Legal Executive and former senior manager with Isle of Man Customs and Excise, where I was (amongst other things) Sanctions Officer (for UN/EU sanctions), Export Licensing Officer and Manager of the Legal-Library & Collectorate Support Section

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