Author’s note: Whilst this account is based on original records and war diaries, it is still ‘work in progress’, and I apologise in advance for any omissions or errors. If anyone has additional information, particularly regarding the Canadian link to the Sherman Octopus, I will be pleased to hear from them. There were also mobile bailey bridge designs using the Sherman; these are covered in a separate article.
By early April 1944 the 8th Army were searching for an alternative method to the Scorpion for breaching minefields, as the fixed-boom flail was proving unreliable in the conditions encountered in Italy. The solution they adopted was to bridge the minefield. The exact origins of this idea have yet to come to light, though the scheme was sponsored by the Chief Engineer and DME of 8th Army. Three 'old' Sherman IIIs were provided for conversion and this was carried out by 1 Canadian Army Tank Workshops. By April 1944 the first prototype had been built, based on a Sherman III chassis and named the Octopus. The original conversion used Class 24 trackway ramps and decking over the tanks hull. The idea was for the tank to drive into a minefield until it hit a mine; the ramps would then be dropped forming a bridge – if necessary further Octopi would cross eventually forming a chain of bridges over the mines.
Trials of the Sherman Octopus were conducted by 1 Assault Regiment RAC/RE and MWEE during May 1944, leading to an order for similar Churchill Octopi conversions for use by the new Assault Regiment. These differed in that they used American M1 steel treadway sections which had a better load rating. They were eventually used not to gap minefields, but in an assault role to bridge the many water obstacles encountered in Italy, being renamed as the Churchill ARK II. Although three Shermans were delivered and according to the Workshops' War Diary completed as Octopus prototypes, later records only refer to one prototype tank. It is possible that the other two were actually used as the basis of the Sherman Plymouth mobile Bailey pusher and carrier tanks, also converted by 1 Cdn Tank Workshops immediately following on from completion of the Sherman Octopus project.
Meanwhile 6th Armoured Division were experimenting with a bridging device for crossing narrow gaps; the Stepping Stone. This consisted of three bridging Cribs clipped together and carried across the front of a Sherman. The only modifications were the removal of the front lights, siren and guards, and the retraction of the co-drivers MG into the hull. The turret was reversed and the Stepping Stone secured on the glacis by a lashing passing through the commanders hatch and secured to the gun breach. Once launched some of the crew and attached RE dismounted and positioned it in the ditch. The RE were very vulnerable as they were expected to travel on the rear deck of the tank.
By the summer of 1944 there was an acute shortage of bridgelaying tanks for the armoured and tank regiments. Valentine Bridgelayers were becoming scarce, they were no longer in production and spares were in short supply. Yet, as the armies advanced north they were encountering more frequent obstacles to be crossed. The Churchill regiments could look forward to the new Churchill Bridgelayer, and initially formed bridging troops with Churchill ARKs and fascine carriers. However, there was no immediate solution for Sherman regiments.
It was decided to supplant, and eventually replace, the Valentine Bridgelayer in Sherman formations with 20 Sherman ARKs derived from the earlier Octopus. This project was delayed by an acute shortage of steel treadway ramps; there seems to have no progress even on converting the original MWEE prototype between June and September 1944. Any treadway that was available was reserved for the Assault Regiment ARKs, and from November 1944 25th Tank Bde also began converting Churchills to ARKs to make up for a shortage of assault equipment.
By November 1944 the shortage of bridgelayers in armoured brigades was becoming acute. Given the obstacles likely to be faced in coming operations the CE of 5 Corps ordered 2nd Armoured Brigade to develop a number of Sherman based bridging vehicles. During November 1944 the Brigade LAD and REME workshops worked on three distinct designs.
The first was a Sherman ARK, based on the Sherman V, of which six were eventually produced. Trials showed it to be suitable, although inferior to the Churchill ARK. The design was similar to the original Octopus, although the ramps were more substantial and had improvements to the carrying and launching mechanism. It was hoped to use American steel treadway ramps, as on the Churchill ARKs, but these were in short supply. An interim plan was for these tanks to operate with decking over the hull, but using fascines fore and aft until ramps became available. In the end the 2nd Armd Bde Sherman ARKs seem to have had custom built ramps rather than steel treadway.
The second vehicle was the Sherman Fascine (or Bolster) Carrier, this time based on a ‘big hatch’ Sherman II hull. The turret was removed, but the turret ring itself was retained. A framework assembly was mounted on the turret ring enabling two ‘bolsters’ (identical to the earlier Stepping Stones) and/or fascines to be carried, the mounting being traversed to launch them over guide rails on the hull front.
The third vehicle was referred to as the Sherman Cut-Down, which was similar to (and in fact preceded) the Sherman Kangaroo. It was also based on a late Sherman II hull, at least in 2nd Armd Bde. Its function was to carry a small party with pioneer tools to work with the fascine carriers, and overcame the limitations of the 6th Armoured Division expedient of carrying working parties on the engine decks of tanks. In 2nd Armd Bde the armoured regiments accepted that they would provide these parties from within their own establishments rather than relying on the attachment of REs. However, there was close support from attached RE Field Squadron troops in training in basic sapper skills and the making of fascines.
2nd Armoured Brigade converted 6 Sherman ARKs, 6 Sherman Cut-Downs and 9 Sherman Fascine Carriers during 1944. At least one Sherman V ARK was used in action at the Marzeno crossing on 24th November 1944 in support of the 9th Lancers. The success of the design prompted the B.RAC at Allied Armies Italy to order comparative trials of the old Octopus prototype against the Churchill ARK, with a view to switching all ARK production to the Sherman. Trials held at 1 Assault Regiment RAC/RE in early December, for which steel treadway ramps were fitted, confirmed that the Sherman was inferior in the assault role and the idea was dropped.
REME records indicate that a total 23 Sherman Fascine Carriers were converted by the end of December 1944. This includes conversions by other brigades, 7th Armd Bde for example using a simplified design.
By early December 1944 all armoured bridging equipment from the tank and armoured brigades was concentrated at Forli under the control of the Assault Regiment RAC/RE. This highlighted a weakness in that the fascine carriers were not fitted with radio, and modifications had to be urgently made. Later in the month the 2nd Armd Bde went into reserve. It’s Sherman bridging vehicles were transferred to other units as follows:
2 Sherman ARKs, 3 Sherman Fascine Carriers and 2 Valentine Bridgelayers to 4th NZ Armoured Brigade
3 Sherman ARKs, 3 Sherman Fascine Carriers and 3 Valentine Bridgelayers to 7th Armoured Brigade
In early 1945 the New Zealanders decided to organise the equipment that had been transferred to them, plus their existing Sherman V Dozers and Valentine Bridgelayers, into 28 NZ Assault Sqn. Other brigades had similar levels of equipment, but operated them as bridging troops and/or dispersed them amongst their regiments. Photos appear in several publications of 2nd Armd Brigade 1944 design ARKs and both 2nd Armd Bde and 7th Armd Bde design Fascine Carriers in NZ service.
For the Spring Campaign a large number of fascine carrier conversions were planned, though it is not clear if all of them were completed. An 8th Army order of 25 March 1945 gives:
2 Armd Bde 6 held. 1 to be transferred from 7 Armd Bde. 3 Cut Downs to be converted.
4 NZ Armd Bde 3 held. 7 Sherman I or II gun tanks converted by Bde workshops.
7 Armd Bde 2 held.
2 Polish Armd Bde 6 Sherman I or II gun tanks to be converted by 664 Tank Wksps
Note that the numbers do not tally with the REME figure of 23 converted by 1944. The only Sherman Is in-theatre were the relatively new Sherman IC Firefly and 105mm Sherman IB. Some of the Sherman II conversions were also on more recent ‘big hatch’ hulls.
2nd Armoured Brigade again gives us more detail. They had been left with only six Fascine Carriers and three Sherman Cut-Downs. The easiest solution to bring the unit back to strength was to transfer one Fascine Carrier from 7th Armoured Brigade, who had partially reequipped with Churchills, and to modify the Cut-Downs to make up the numbers. These conversions were to the “7th Armoured Brigade Pattern”. As the turret ring had been removed in the original Cut-Down conversion these were simpler than the 2nd Armoured Brigade’s 1944 design, having a fixed framework built over the hull, capable of carrying two fascines and launching them over the front of the tank. At least one photo shows a vehicle of this design carrying a bolster on the rear deck.
2nd Armoured Brigade also needed ARKs. Rather than replicate their original design, they set about building an improved prototype, again based on the Sherman V, which after development became the Twaby ARK. Work on this new ARK started only two weeks after the brigades original bridging equipment had been dispersed to other units. The main improvement in design was that the ramps could now be carried flat on the top deck of the tank, making the approach march a lot easier, although the assistance of another tank using a tow cable was required to get the ramps into launching position. After trials a further 4 Sherman ARKs were converted. Surviving photos show the Twaby Ark fitted with Platypus Grousers.
AFV Returns for 7 April 1945, immediately before the Spring offensive began, shows the following totals of Sherman bridging vehicles in 15th Army Group :
6 Armoured Division: 3 Fascine Carriers
6 South African Division 2 Bridgelayers
2 Armoured Brigade 4 ARKs and 9 Fascine Carriers
7 Armoured Brigade 2 Fascine Carriers
25 Armd Engr Bde 8 Bridgelayers
ARG 1 ARK, 6 Bridgelayer and 6 Fascine Carriers
In Workshops 2 ARKs and 2 Bridgelayers
The Bridgelayers are tanks converted for use with Plymouth and Brown mobile Bailey bridges. The ARKs and Fascine Carriers of 28th NZ Assault Sqn are missing, possibly as it was an engineer rather than armoured unit.
Records for the April 1945 Spring Campaign provide many examples of fascines in use, but there is no record of Sherman ARKs being used, although there was brief consideration just before the campaign started of supplying one Sherman ARK to 5 Army. Very often these vehicles travelled with the leading armour to help maintain the pace of advance, the armoured engineers travelling further back with their more specialised vehicles and being called forward when a more complex assault crossing of an obstacle was required.
It is worth noting that the Sherman ARKs and Fascine Carriers frequently operated with Sherman V Dozers from the same unit, equipped with the US M1 dozer kit. The British armoured engineers regarded the diesel powered Sherman III as the most suitable, and were exclusively equipped with this version. The Sherman V, which REME favoured due to its stronger clutch, equipped the armoured regiments. The British considered the radial engine models as unsuitable for dozing as their engines required sustained high revolutions at low speeds to deliver enough power - one report refers to three American M4A1 dozers on loan as mechanically ‘useless’ for the task. The British claimed the Steel Chevron was the only suitable track for a Sherman Dozer, whereas the Americans preferred rubber block track.
Copyright Pete
Andrews 2004