Following Japan's entry into the Second World War in 1941, the Labour Government reluctantly acquiesced to the establishment of a bipartisan War Administration in July 1942, consisting of seven Labour Ministers and six National Ministers. Sidney Holland served as the Deputy Chairman of the short-lived War Cabinet, which collapsed in September 1942 after the National Party objected to Labour's handling of an unofficial miners' strike in the Waikato region that same month. Holland's decision strained relations with both the Labour Government and several National MPs including Gordon Coates and Adam Hamilton, who withdrew from the National caucus and rejoined the War Cabinet as independents. The resignation of these two former Reform Party MPs helped strengthen Holland's control over the party caucus and organization.