fought in was the Battle of Delville Wood in 1916. (See South African Army in World War I.) South Africans also saw action with the Cape Corps as part of the Egyptian Expeditionary Force in Palestine. (See Cape Corps 1915 - 1991) Military contributions and casualties in World War I With a population of roughly 6 million, between 1914 - 1918, over 250,000 South Africans of all races voluntarily served their country. Thousands more served in the British Army directly, with over 3,000 joining the British Royal Flying Corps and over 100 volunteering for the Royal Navy. It is likely that around 50% of white men of military age served during the war. More than 146,000 whites, 83,000 black Africans and 2,500 Coloureds and Asians served in either German South-West Africa, East Africa, the Middle East, or on the Western Front in Europe. Suffering roughly 19,000 casualties, over 7,000 South Africans were killed, and nearly 12,000 were wounded during the course of the war. Eight South Africans won the Victoria Cross for gallantry, the Empire's highest and prestigious military medal. The Battle of Delville Wood and the sinking of the SS Mendi being the greatest single incidents of loss of life. The assistance that South Africa gave the British Empire was significant. Two German African colonies were occupied, either by South Africa alone or with significant South African assistance. Manpower, from all races, helped Allied operations not just on the Western Front and Africa but also in the Middle East against the Ottoman Empire. South Africa's ports and harbours on the Home Front were a crucial strategic asset when conducting a war on a global scale. Providing important rest and refuelling stations, the Royal Navy could ensure vital sea lane connections to the British Raj, and the Far East stayed open. Economically, South Africa supplied two-thirds of gold production in the British Empire, with most of the remainder coming from Australia. At the start of the war, Bank of England officials in London worked with South Africa to block gold shipments to Germany, and force mine owners to sell only to the British Treasury, at prices set by the Treasury. This facilitated purchases of munitions and food in the United States and neutral countries. World War II Declaration of war against the Axis On 4 September 1939, the United Party caucus refused to accept Hertzog's stance of neutrality in World