The HNP which stands for Herenigde Nasionale Party means Reunited National Party and was the opposition to the United party in South Africa in 1938. The HNP was headed by D F Malan, a pastor. The United Party had led the South African government since it was founded in 1933.
When World War II (WWII) broke out (1939), some South Africans felt that SA should have sided with the Germans as they were of German descent. However, Jan Smuts persisted and sided with the Allies. South Africa was a British Territory at the time and fought in Madagascar, Ethiopia and even Italy. Jan Smuts the leader of the ruling United Party had a working relationship with Joseph Stalin of Russia during WWII. The USSR was also one of the allies fighting Nazi Germany.
Jan Smuts shared leadership of the United Party with JBM Hertzog. Hertzog resigned when Smuts joined the "Allies" as he did not want involvement on either side in WWII. Hertzog joined forces with the newly formed HNP, a significant move which changed SA politics as he was well-liked by some. The HNP undertook to impose strict racial segregation and undertook to write it into Law. Such was their election campaign and it began what would later become "Apartheid," which means "separateness" in Afrikaans. Afrikaans is one of the 11 official languages of South Africa and the language which the HNP promised would become the language of choice in business once they won the election.
The "white" electorate became disillusioned by economic and domestic difficulties after WWII; hence Jan Smuts' United Party lost favor, especially as the United Party allowed British immigrants into the country and the South African whites felt that the British were taking over and had to be stopped. The HNP exploited this new "racist scare." The fact that Hertzog had joined the HNP also strengthened their oppositional position.
By 1948, the HNP won the election, having formed a coalition with The Afrikaner Party and ousting the United Party. Black voters were basically non-existent, having been banned from voting since the 1930s, thus had no say, and Colored and Indian voters were very restricted in their voting rights. The vote was therefore one-sided, but the Nationalists were sure they had "purified" their party; they won by a narrow margin whereupon they encouraged German and Dutch immigrants and blocked immigration from Britain.
The decision by Jan Smuts to join the Allies in Europe and fight against Germany contributed to the split within his party. The future of South African politics changed for ever.