Ever since Britain had taken control of South Africa from the Netherlands in the Napoleonic Wars, it had run afoul of the Dutch settlers who further away and created two republics of their own. The British imperial vision called for control over the new countries and the Dutch-speaking "Boers" (or "Afrikaners". The Boer response to the British pressure was to declare war on 20 October 1899. The 410,000 Boers were massively outnumbered, but amazingly they waged a successful guerrilla war, which gave the British regulars a difficult fight. The Boers were landlocked and did not have access to outside help. The weight of numbers, superior equipment, and often brutal tactics eventually brought about a British victory. To defeat the guerrillas, the British rounded up their women and children into concentration camps, where many died of disease. World outrage focused on the camps, led by a large faction of the Liberal Party in Britain. However, the United States gave its support. The Boer republics were merged into Union of South Africa in 1910; it had internal self-government but its foreign policy was controlled by London and was an integral part of the British Empire.