A Kangaroo was a World War II

World War II

World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

 Commonwealth

Commonwealth of Nations

The Commonwealth of Nations, normally referred to as the Commonwealth and formerly known as the British Commonwealth, is an intergovernmental organisation of fifty-four independent member states...

 or British

United Kingdom

The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

 armoured personnel carrier

Armoured personnel carrier

An armoured personnel carrier is an armoured fighting vehicle designed to transport infantry to the battlefield.APCs are usually armed with only a machine gun although variants carry recoilless rifles, anti-tank guided missiles , or mortars...

 (APC), created by conversion of a tank

Tank

A tank is a tracked, armoured fighting vehicle designed for front-line combat which combines operational mobility, tactical offensive, and defensive capabilities...

 chassis. Created as an expedient measure by the Canadian Army, the Kangaroos were so successful that they were soon being used by British forces as well. Their ability to manoeuvre in the field with the tanks was a major advantage over earlier designs, and led to the dedicated APC designs that were introduced by almost all armies immediately after the war.
In July 1944, Harry Crerar

Harry Crerar

Henry Duncan Graham "Harry" Crerar CH, CB, DSO, KStJ, CD, PC was a Canadian general and the country's "leading field commander" in World War II.-Early years:...

's First Canadian Army

First Canadian Army

The First Canadian Army was the senior Canadian operational formation in Europe during the Second World War.The Army was formed in early 1942, replacing the existing unnumbered Canadian Corps, as the growing number of Canadian forces in the United Kingdom necessitated an expansion to two corps...

 was concerned by manpower shortages and Lieutenant-General Guy Simonds

Guy Simonds

Lieutenant General Guy Granville Simonds, CC, CB, CBE, DSO, CD was a Canadian Army officer who commanded the II Canadian Corps during World War II. He served as acting commander of the First Canadian Army, leading the Allied forces to victory in the Battle of the Scheldt in 1944...

, commander of the II Canadian Corps

II Canadian Corps

II Canadian Corps was a corps-level formation that, along with I Corps and I Canadian Corps , comprised the First Canadian Army in Northwest Europe during World War II.Authorization for the formation of the Corps headquarters became effective in England on...

, devised Kangaroos as a way of reducing infantry losses.

The first Kangaroos were converted from 102 M7 Priest

M7 Priest

The 105 mm Howitzer Motor Carriage M7 was an American self-propelled artillery vehicle produced during World War II. It was given the official service name 105 mm Self Propelled Gun, Priest by the British Army, due to the pulpit-like machine gun ring, and following on from the Bishop and...

 self-propelled gun

Self-propelled gun

A self-propelled gun is form of self-propelled artillery, and in modern use is usually used to refer to artillery pieces such as howitzers....

s of three field artillery regiments of the 3rd Canadian Infantry Division

3rd Canadian Infantry Division

The Canadian 3rd Infantry Division was an infantry division of the Canadian Army from 1940 to c.1945.- History :The formation of the division was authorized on 17 May 1940...

 who were involved in the initial assault on 6 June 1944.