At the beginning of the Second World War the British Army was equipped with two simple fuel containers: the container made of pressed steel, and the container made from tin plate. The 2-gallon containers were relatively strong, but were expensive to produce. Manufactured primarily in Egypt, the 4-gallon containers were plentiful and inexpensive, but they had a tendency to leak after minor damage. Early 4-gallon containers were packed in pairs in wooden cases. When stacked, the timber framing protected the tins and prevented the upper layers of tins from crushing the lower. As the war progressed, the wooden case was replaced with either thin plywood or cardboard cases, neither of which provided much protection. 4-gallon containers carrying fuel were hazardous to the cargo ships carrying them. The leaking fuel would accumulate in cargo holds. At least one such ship exploded.