On the 1 September 1939 Germany invaded Poland. The Prime Minister Neville Chamberlain addressed the Commons the following day but, against expectations, did not announce that Britain had declared war.
Arthur Greenwood, acting as Labour Leader due to Clement Attlee’s ill health, did much for Labour’s reputation when he spoke in favour of ‘unity’ and an early declaration of war.
On the 3 September, with war declared, Greenwood pledged Labour’s ‘wholehearted support’ and ‘full contribution to the national cause’.
The majority of Labour MPs, like the rank and file, supported Britain’s entry into the war.
They were less divided than they had been at the outbreak of World War I. The traditionally pacifist Independent Labour Party had disaffiliated in 1932. This time the reason for declaring war was less contentious.
A small group of around twenty MPs, known as the Peace Aims Group, did voice their dissent and press for a negotiated peace.