Mobilisation When
I Corps Headquarters mobilised on the outbreak of war in September 1939 it was assigned the following units as
I Corps Troops Royal Engineers (I CTRE) under
Lieutenant-Colonel G.R. Pim as Commander Royal Engineers (CRE): • 13 Corps Field Survey Company at
Southampton from the Survey Battalion, RE (
Regular Army) • 102 (London) Army Field Company at
Bethnal Green (
Supplementary Reserve) • 105 (West Lancashire) Corps Field Park Company at
Liverpool (Supplementary Reserve)
Battle of France I Corps embarked for France with the
British Expeditionary Force and began taking over a section of the frontier defences on 3 October 1939. I CTRE spent the early weeks on tasks around Corps HQ in the
Douai area. Then the engineers spent the
Phoney War period working on defensive positions. I CTRE attached 221st Fd Co to
1st Division as an additional field company. Its role on the outbreak of hostilities, in conjunction with 1st Division's bridging section, was to open the road from
Tournai to
Brussels and maintain an important canal crossing. When the
German offensive in the west opened on 10 May 1940, the BEF advanced into Belgium in accordance with
'Plan D'. 221st Field Co found itself in the lead, advancing ahead of the scouting armoured cars. However, the
German Army broke through the
Ardennes to the east, forcing the BEF to withdraw again, and by 19 May the whole force was back across the
Escaut and then went back to the so-called 'Canal Line'. The engineers carried out as many bridge demolitions as possible to delay the German advance. 221st Field Co was tasked with destroying bridges along a 10 km stretch of the
Brussels–Charleroi Canal to delay the German advance, then to prepare a 'stop line' on the
La Bassée Canal. By 26 May the BEF was cut off and the decision was made to evacuate it through
Dunkirk (
Operation Dynamo). I Corps acted as
rearguard, the sappers blowing bridges and cratering roads to form a defensive perimeter. Because it was unable to fulfil its usual role of supplying maps, 13th Field Survey Company was sent with the Corps armoured car regiment,
12th Lancers, on 27 May to defend
Veurne, where the Belgian commander insisted that he required no help. However, on 29 May the Belgian Army capitulated, leaving a wide gap in the perimeter along the
Yser. This gap was filled by the 12th Lancers, a few French troops, and by 13th Field Survey Company and 101st Field Company of I CTRE. They succeeded in blowing all the Yser bridges except at
Nieuwpoort, where the Germans already had a bridgehead despite the efforts of the Lancers and Survey Company. However, the enemy were prevented from exploiting this bridgehead. The BEF fought to maintain the shrinking perimeter round Dunkirk while the evacuation went on each unit in turndestroying its vehicles and stores before boarding a variety of vessels. One party of 221st Fd Co was on the
Queen of the Channel, which was bombed and sunk on 28 May: the passengers and crew were picked up and taken to England aboard the
Dorrien Rose. Another party from the company arrived in England the following day on
HMS Greyhound.
Home Defence After the evacuation, I Corps was reassembled in
Northern Command, becoming responsible for both field forces and coast defence artillery on the Yorkshire and Lincolnshire coast. I CTRE was reformed, but 13 Field Survey Co transferred to Northern Command HQ • 240 (Lowland) Field Co –
from II CTRE Indeed, I Corps' staff had been studying the engineering problems of an opposed landing since December 1941.
Normandy I Corps was an assault formation for
D Day, attacking with
3rd Division at
Sword Beach and
3rd Canadian Division at
Juno Beach. While I CTRE under its CRE, Lt-Col R.W.F. Poole, was kept under the direct command of I Corps HQ, a platoon of 19th Field Co was attached to 3rd Canadian Division to assist with beach obstacle clearance once the landings had been made. Having failed to seize
Caen on D Day, I Corps was engaged in heavy fighting in the area for several weeks. I CTRE's most important role was to increase the bridge capacity across the
River Orne and the
Caen Canal into the bridgehead captured on D Day by
6th Airborne Division. By the beginning of July three pairs of bridges were in place: • A Class 40 Bailey Pontoon bridge ('York I') built over the locks at
Ouistreham by 234 Fd Co and 7 Fd Co (of 6th Army Troops RE), and its continuation ('York II') over the Orne by the same companies • The bridges captured by the airborne forces on D Day,
Pegasus and
Ranville • Two Class 40 bridges to duplicate Pegasus and Ranville ('London I' and 'London II'), built on 10–11 June by 71 Fd Co and 263 Fd Co (of
XII CTRE) Now these were to be supplemented by further work, for which task Poole also had at his disposal five field companies from 18th GHQ Troops, RE (74, 84, 91, 173 and 213) and two from 8th GHQ TRE (89 and 90): • Replacement bridges at Ouistreham Locks ('Tower I' by 19 Fd Co) and its continuation over the Orne ('Tower II' by 234 and 240 Fd Cos) • Strengthening Pegasus and Ranville to take Class 40 loads • A pair of Class 40 Bailey bridges ('Tay I' and 'Tay II') at
Blainville-sur-Orne, upstream from Pegasus and Ranville, by 89 and 90 Fd Cos. This additional work had to be carried out in secret, so that five Class 40 routes would be available for
VIII Corps' tanks to move into the Airborne bridgehead to launch
Operation Goodwood on 18 July. Stores were brought up in advance and concealed, and the actual construction was carried out during the night of 17/18 July. The associated work involved a great deal of improvement to roads and tracks, and lifting of minefields that blocked the routes of advance, and the RE of the attacking divisions had to help out. Although 'Goodwood' failed to achieve a breakthrough, the engineering operations provided a firm base from which I Corps advanced eastwards once the breakout from Normandy was finally achieved in late August. By this time,
First Canadian Army had been activated, and I Corps came under its command.
Clearing the ports First Canadian Army's next task was to liberate the
Channel ports and make them available to supply 21st Army Group. The first of these were captured by I Corps:
St Valery-en-Caux on 4 September and
Le Havre, in
Operation Astonia, 10–12 September. The initial attack at Le Havre was launched by
56th Brigade of
49th (West Riding) Infantry Division, supported by 240 Fd Co of I CTRE and led by the
AVREs of
42 Assault Regiment, RE. 'Astonia' was very much a sapper's operation: the port was heavily fortified, but despite setbacks the set-piece operation went well, the defences were overrun and the town captured in 48 hours. First Canadian Army then moved on to
Antwerp: the city had quickly fallen to 21st Army Group's advanced elements, but there was a prolonged campaign to clear the approaches to the port, after which I Corps held the line of the
River Maas for the winter.
Germany In March 1945 21st Army Group stormed across the
Rhine and advanced rapidly across Germany. I Corps' role was limited to liberating the Netherlands and securing the lines of communication for 21st Army Group. The
German surrender at Lüneburg Heath on 4 May did not end the work for the sappers: for many months they were engaged in repair and restoration of essential services behind the armies and in the occupied zone of Germany. The CE of I Corps had a month to devise a method of clearing 130 wrecked bridges from the
Weser to open it to river traffic. On 21 May 1945, I Corps was redesignated I Corps district, responsible for
Rhine Province and Westphalia as part of
British Army of the Rhine (BAOR). I Corps was disbanded in 1947; its RE companies all appear to have been disbanded in 1945–6. ==Postwar==