The Churchill AVRE (Armoured Vehicle Royal Engineers) became one of the many offshoots to arise from the British Army's famous Churchill Infantry Tank line (detailed elsewhere on this site). The new design took the basic Churchill tank chassis and hull and converted it to an engineering-minded platform to help in obstacle-breaching and beach-clearing initiatives. The concept was brought about by a Canadian Army engineering officer following the disastrous Allied amphibious landings at Dieppe in August of 1942 in which engineering units were highly vulnerable to enemy fire from all sides while attempting to clear the beaches for the main landing force.
A converted tank offered engineering forces the ability to work while under the protection of armor. In the AVRE conversion process, the original tank's main gun was to be replaced with a large-caliber demolition weapon (mortar) which could also be operated (fired, loaded) from the within the protective confines of the turret. The vehicle, more or less, retained all of the functionality of the original Churchill Infantry Tank with modifications made simply to suit the engineering role - a practice continued today on modern Main Battle Tanks (MBTs).
For the Churchill AVRE conversion process, special kits were devised for expediency and both government facilities and private industry factories played a role in generating the new vehicles for widespread service in the war. The Churchill Mk III and Mk IV production models were the primary chassis/hulls used in the AVRE conversions.
The War Office was convinced of the value of the concept and the selection of host vehicle naturally fell to the Churchill series - it was available in large quantities and had a proven drivetrain and battlefield capabilities for the engineering form to succeed. The modification process saw the internals of the turret completely reworked with engineering-minded components added. The tank's main gun was removed from the front turret face and, in its place, a Petard mortar was installed alongside a 7.92mm BESA coaxial machine gun (the latter for local defense). The mortar - given the nickname of "Dustbin" - fired a massive 40lb, 11.4" demolition charge out to 80 yards for general obstacle-clearing and fortification-busting.
Deep wading gear could be installed for amphibious operations in the form of engine and crew air vents rising higher than the turret roof line- allowing the vehicle to traverse water sources when assailing beaches. Additionally, an anti-tank mine plow was fitted at the bow for clearing below-ground mines when hitting contested positions and a "Porpoise" palette-type unit could be fitted at the rear of the vehicle for towing heavier gear ashore.
The vehicle was soon in service with the 79th Armoured Division, seeing its baptism-of-fire during the June 1944 landings at Normandy, France. Their success in the operation was such that the vehicles quickly established themselves as the standardized engineering platform of the British Army for the duration of the war and for some time later. In practice, the AVRE brigades were able to accomplish all manner of mission-critical actions including covering soft terrain by distribution of fascine, transporting much-needed equipment and supplies to Forward Operating Positions (FOPs),clearing paths through minefields, and general destruction of fortified locations with its massive mortar weapon. Beyond the local protection the vehicles provided their crews, the framework of the Churchill meant that the vehicle could keep pace with the general land force and move about cross-country when needed. Its inherent drive power also opened the design to transportation of all manner of war goods which doubled its strategic value in-the-field considerably.
The Churchill AVRE family was eventually superseded in the post-World War 2 period by the Centurion AVRE, itself built upon the framework of the classic Centurion MBT.