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D-day Exercises- Operation “Prank” March 1944

The whole plan for D-day relied on establishing relatively safe Beachheads which would enable men and weaponry to access the Normandy beaches and move inland. In the various campaigns in Italy, Sicily and North Africa much had been learned about balloons and  beach landings. However it was essential that the beach landing in Operation Overlord be as successful as possible. It was decided to run a full scale exercise to test the ability of the Beach Balloon Units to land, establish balloon sites and rapidly let up balloons to defend from air attack a series of sites on a beach.  No.51 Beach Balloon Unit was chosen to practice a first assault on a sandy beach. This gave the troops involved experience of  a “wet shod” landing, and the embarkation and carrying of  balloons on Landing Craft. Balloons were embarked from the Admiralty Hards and in an effort to provide a low radar signal it decided to fly the Mk VI balloons in two groups, one group flying from the point of attachment on the Landing Craft rail which equated to zero feet and the other group at 100 feet.  

The exercise was begun on 7^th March 1944 when two Landing craft had a balloon each which was attached to the Landing Craft rail which equated to zero feet. On 8^th March 1944 a further 18 balloons were due to be embarked but severe winds meant that not a single balloon could be embarked at the Admiralty Hards at zero feet or 100 feet. To try and make the exercise work the Barrage Balloon Squadrons from Portsmouth were ordered at first light, to ferry the balloons by small craft directly to the Landing Craft at their anchorages. This enabled 24 balloons to be flown at 100 feet on strops. The two balloons previously attached to the Landing Craft rail on 7^th March 1944 became casualties. It became obvious that the disembarking of the Light Portable Winch with two men was very difficult as it weighed around 240 lb, and as a result on the 8^th March 1944 each Landing Craft with a balloon carried two men and a Light Portable Winch drum only. The two Bedford 4 X 4 vehicles that were also embarked were loaded with Light Portable Winches on the scale of two winches per  five balloons.

A reconnaissance party consisting of one Flying Officer and five  N.C.O.’S embarked on a Landing Craft Infantry with a light Anti-aircraft reconnaissance party.

On the 9^th March the convoy  sailed at 2000 hours, on beaching the reconnaissance party chose suitable balloon sites and waited on the shore to guide the balloon beach crews to the selected balloon site. The first Landing Craft arrived on the beach at 0830 hours and all 24 balloons were got ashore. The majority of crews got ashore “dryshod” on the top of army vehicles. The balloons were raised from the winch drums using a crowbar as a spindle. The first balloon was at operational height within 15 minutes of landing and by 1400 hours all the balloons were ashore and at operating height. There had been a delay in landing the balloon servicing vehicles and the Beach Balloon Unit Commander. This meant that at last light it was impossible to get any balloons down until the servicing vehicles were ashore. They finally landed at 2100 hours and four balloons were close-hauled by Light Portable Winch or flexible drive on the vehicles. The remainder of the balloons were left flying on orders of the Beach Commander.

On the 10^th of March 1944 all balloons were hauled down and deflated, packed up and returned to their stations by road. This ended Exercise “Prank”.

There were lessons learned:-

1. The balloons could not be easily transported by attachment to the rail of the Landing Craft.

2.Even in the event of fine weather it was doubtful that balloons could not be flown successfully at 100 feet and it was thought that 300 feet might be better and this needed investigation.

3.If the ground speed of the wind was over 30 m.p.h. it was thought that embarkation of balloons at any height was not possible. It was decided to experiment with ways of ferrying balloons to the Landing Craft at their rendezvous anchorages, when the weather permitted.

4.If balloons were embarked from the Admiralty Hards at 300 feet or over they could be attached to the Admiralty Winch on board the Landing Craft and hauled down to 100 feet for the voyage in an effort to avoid radar signals.

4.It was realised that if the Landing Craft were moored at their rendezvous for more than 48 hours before sailing, the balloons on eventually landing, will not be as efficient as they could be. Hydrogen loss was likely. They would need topping up before the convoy sailed. It would be possible to have a hydrogen cylinder on board but the exercise of topping up on a Landing Craft would be very difficult unless the sea was dead calm.

5.This meant that the only solution was to ensure that balloons were only embarked during the 24 hours before the convoy sails. This also means that the concept of ferrying balloons  and transferring them to a Landing Craft needed to be explored and given serious consideration.

6.This exercise  showed that whatever embarkation procedure was finally adopted, the organising of the rigging, inflation and embarkation of balloons would entail detailed planning in liaison with the many different services and authorities on the spot. Such planning and organising had to take place while the Beach Ballooon Unit with its Officers and vehicles were in the Marshalling yards or Concentration areas. Balloon Command had to ensure there were competent Officers, preferably at the rank of Squadron Leader, temporarily available during the period D-8 to D to assume responsibility for producing the balloons in perfect condition to the Beach Balloon unit crews on the correct craft and at the right moment. This needed close liason with the local Naval and Military Authorities.

7.Once the Landing Craft were clear of the shore and the wind eddies produced by dock installations, no undue difficulty was to be anticipated with the balloons. In light winds the balloons could fly at 100 feet but in moderate to strong winds they would need a clearance to fly at 300 feet to decrease the risk of loss.

8.The actual beach landing was to be carried out by co-operation between the R.A.F. balloon crews and the other personell on board the Landing Craft. Balloon crews could get ashore on any vehicle leaving the Landing Craft. If the vehicle became swamped with water and inoperable the balloon crews could still wade ashore with the balloon.

9.Provided the reconnaissance party had selected a good site the balloons should be at full operational height within 15 to 30 minutes of beaching depending on the distance from the landing point.

10.Exercise “Prank” showed that two airmen could not get a Light Portable Winch ashore unaided. The winch would delay the beaching of the balloon and as a result the balloon was to be brought ashore with only the winch drum and a crowbar used as a spindle to enable the balloon to be let up to operating height.

11.The balloon servicing vehicles were to be carrying two Light Portable Winches per five balloons and once these vehicles were ashore the use of the winches could then begin. These vehicles had to cross the channel on the same wave as the balloons. Exercise “Prank” showed that there was a risk of vehicles not getting ashore on time due to Landing Craft issues and this risk had to be minimised by phasing forward the third vehicle of each Beach Balloon Unit to the same wave. This vehicle was to have two winches per five balloons.

12.Beach congestion was to be avoided and a reconnaissance party of one officer and five N.C.O.’s was essential. This would reduce the number of personnel available to transport and land the balloons. If 240 balloons were to be landed the initial landing would be limited to 200 balloons. This should be acceptable as the balloon protection for Mulberry was not needed until D+1 at the earliest. The efficiency of the balloons would be increased if sufficient Hydrogen cylinders could be got across with the initial balloons.

13.Provided the three vehicles per thirty balloons could be phased into the initial wave some fifteen Hydrogen cylinders might be carried. It was no exaggeration that this might well make the difference between success and failure, should bad weather interfere with the supply of inflated balloons flown over from this country.

14.To minimise the reduction in the number of balloons landed owing to the necessity for a reconnaissance party it was essential that drivers or additional balloon operators should be established for each of the three vehicles.

15.The major problem for Balloon Command was that the inflated balloons had to be provided and embarked at the right time and in the right place and in the correct quantities in the face of possible weather hazards. It was thus essential that Balloon Command knew

·       the Admiralty Hards from which the Beach Balloon Unit  balloons would embark.

·        The number of balloons to be embarked from each Hard.

·       The rendezvous anchorages for the Landing Craft after leaving the Hards.

 Once this information was known Headquarters had to temporarily lay on enough fully competent Officers to deal with the many problems that were bound to arise at each point of embarkation.

It could not be ruled out that it would be needed to ferry balloons out to get them onto a Landing Craft safely and in prime condition for the Operation, and the provision of the craft and location of the necessary personnel needed to be investigated thoroughly and the number of craft needed had to be calculated. A fast craft making 20 knots could ferry out up to 20 balloons per day if the distance between the balloon inflation point and the Landing Craft anchorage was less than five miles offshore.

This was the analysis of those involved in assessing exercise “Prank”. It seems that nobody questioned what would happen to these plans if those landing on the beaches came under fire and come under fire they did. It is hard to decide if the planning authorities were being naïve or had decided not to consider this in official documents to prevent possible panic and loss of troop morale.

One outcome of some the balloon delivery for D-day was to introduce Operation Plumtree where a vessel was anchored offshore with a number of balloons inflated and awaiting collection. The balloons could then be picked up one at a time by Landing Craft and was likened to picking plums off a tree, hence the name Plumtree.

On the 24^th March 1944, D-day was just nine weeks away and a Memorandum was issued stating the position as known at the time.

Eight Beach Units of 30 balloons had been formed and trained within Balloon Command but only seven had been established and the remaining Unit was being established. It seems the 21 Army Group had not actually given in their request for balloon protection but it was suggested that they would require balloon protection of sixty balloons to each Beach Squadron area, plus an additional sixty for protection of the Mulberry area. Suggesting that 240 balloons would be needed.

The Allied Naval Commander Expeditionary Force was asked about how soon after the initial assault balloons could be flown across the Channel without the British prematurely giving away their intentions to the enemy.  The Radar experts had explained that the balloons could only be flown at 100 feet when 7 miles behind the initial assault wave. It was expected that 105 balloons could be sent on the first tide and 115 balloons on the second tide.

As D-day unfolded it was ruled that as soon as landing strips were operational there would be specific balloon restrictions in place. No balloons were to be flown within 2,000 yards of any landing strip. There was to be an approach funnel at the end of each strip and there was to be no obstruction from balloons above a 1 in 20 start line from the rear end of the strip. Balloon cables at the inner edges of this funnel were to be marked with coloured Streamers at 100 feet intervals and then at 500 feet intervals above 500 feet. Balloons were not to be flown higher than 500 feet below the lowest cloud base. 

Before the arrival of the Headquarters 2^nd Tactical Air Force on the Continent the following Beach Squadrons, Beach Balloon Squadrons and Balloon Flights were to be in place.

Beach Squadrons Nos. 1, 2 and 3 were to be phased in by the Army and go in with the assault.

Beach Squadron No.4 was held in reserve at Old Sarum.

Beach Balloon Squadron No. 974 was to go in with No.2 Beach Squadron.

Beach Balloon Squadron No. 976 was to go in with No.1 Beach Squadron.

Beach Balloon Squadron No. 980 was to go in with No.4 Beach Squadron.

Beach Balloon Squadron No. 991 was for Mulberry and was to go in on D-day + 4.

Port Balloon Flight No.104 for Yapton was to go in on D-day + 6.

Port Balloon Flight No.103 for Croxdale was to go in on D-day + 20.

The following Forces using  various Landing Craft arriving on D-day would fly R.A.F. balloons.

(L.S.T. means Landing Ship Tank and L.C.T. means Landing Craft Tank )

The potential for success of the D-day invasion was always questionable but the balloon protection provided, despite many issues and difficulties, was undoubtedly a major reason for the success of Operation Overlord.

Peter Garwood 2023

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