Hertzog and the South African Party under Jan Smuts merged to form the United Party, which won 111 of the 150 seats in the South African general election, 1938 with Hertzog as prime minister.
When the United Kingdom declared war on Germany in 1939, Hertzog proposed to his party and parliament that South Africa remain neutral.
This was defeated and Hertzog left the government to be replaced by Smuts with South Africa joining the Allies.
Initially, the differences between the more moderate Hertzog group and Gesuiwerde Nasionale Party seemed insurmountable and so the Volksparty was formed with Ben Schoeman elected as the chairman of the party on 9 December 1939.
[1] After difficult negotiations with Malan, the joint opposition called itself Gesuiwerde Nasionale Party of Volksparty (Purified National Party or People's Party) nominally under Hertzog's leadership from January 1940.