Ground forces needed a bridge that could be quickly assembled and could carry the heavy loads demanded by modern warfare. Donald Bailey, a British structural engineer came up with a solution to solve these problems. The Bailey Bridge used prefabricated panels and parts and could be assembled with manpower alone using simple tools in a matter of hours.

After a bridging demonstration in June 1942, LCol J.R.B. Jones was instrumental in its selection for use by the Canadian Army. LCol Jones wrote, "Fourth Canadian Armoured Division, with its five thousand tanks, armoured vehicles, guns and trucks, was a powerful striking force - but only while it had its mobility. In spite of the terrible ground and road conditions of the low countries, while we fought through blown bridges, mines, craters, road blocks, and peat bogs, the Division maintained its mobility, because of the Bailey Bridge".

The Bailey Bridge changed the war in Europe, and as Field Marshal Montgomery said, "Without the Bailey Bridge, we should not have won the war".

Montgomery added, "Bailey Bridging made an immense contribution towards ending World War II. As far as my own operations were concerned, with the Eighth Army in Italy and with the 21st Army Group in North-West Europe, I could never have maintained the speed and tempo of forward movement without large supplies of Bailey Bridging."

The German Army had nothing like it. Donald Bailey received the knighthood for his efforts in 1946.

Although the Bailey Bridge was somewhat complex to build it was more versatile than the bridges that preceded it. It could be built as a raft, pontoon bridge or fixed-span structure. Bridge panels were 10 feet long and could be lifted by a six-man crew. The roadway which ran between the panels was supported by transoms which could be lifted by eight-man crews. The average length of a typical bridge was 30m.

The basic type of Bailey Bridge called for one row of panels each side of the roadway. These could be increased to strengthen the bridge. In Italy, it was not uncommon for Bailey Bridges to be built with three rows of panels on each side of the roadway.

If the engineers expected large loads, it was possible to build up by adding stories to the underlying rows. A bridge designed for heavy loads would take more time to build, but could be constructed from the same bridging equipment. Load-carrying capacity of a bridge could be adapted using this method to support from between thirty to eighty tons.

The Bailey provided a solution to the problem of German armies destroying bridges as they retreated. The longest Bailey Bridge built by the Allies during the Italian Campaign was 330m long and was constructed over the Sangro River in Dec 1943.

A Bailey Bridge constructed over the Rhine River in Germany in 1945 by the Royal Canadian Engineers and nicknamed the "Blackfriars Bridge", was 560m in length, the longest Bailey bridge ever constructed.

In all, over 600 firms were eventually involved in manufacturing components for the bridge, and over 200 miles of bridges were constructed during the war. As many as 2,500 Bailey bridges were built in Italy and Sicily, and another 2,000 in Europe and Asia.