Operation Ironclad
During World War II, Northern Rhodesian military units participated on the side of the United Kingdom. Specifically, Northern Rhodesian forces were involved in the East African Campaign, the Battle of Madagascar and in Burma. Later in the war, the British government's Ministry of Supply entered into agreements with the Northern Rhodesian and Canadian copper mines to supply all the copper needed by the armed forces for set prices. This removed free competition and therefore kept prices down; as British companies, the main copper producers were also subject to the Excess Profits Tax. However they did have a guaranteed market, and in 1943 the Ministry of Supply paid half of the cost of an expansion programme planned for the Nchanga mine.