The shift to guerrilla warfare drove the US Army to adopt counter-insurgency tactics. Civilians were given identification and forced into concentration camps with a publicly announced deadline after which all persons found outside of camps without identification would be shot on sight. Thousands of civilians died in these camps due to poor conditions. 20th century Second Boer War Asymmetric warfare featured prominently during the Second Boer War. After an initial phase, which was fought by both sides as a conventional war, the British captured Johannesburg, the Boers' largest city, and captured the capitals of the two Boer Republics. The British then expected the Boers to accept peace as dictated by them in the traditional European manner. However instead of capitulating, the Boers fought a protracted guerrilla war. 20,000-30,000 Boer guerrillas were only defeated after the British brought to bear 450,000 imperial troops, about ten times as many as were used in the conventional phase of the war. The British began constructing blockhouses built within machine gun range of one another and flanked by barbed wire to slow the Boers' movement across the countryside and block paths to valuable targets. Such tactics eventually evolved into today's counterinsurgency tactics. The Boer commando raids deep into the Cape Colony, which were organized and commanded by Jan Smuts, resonated throughout the century as the British adopted and adapted the tactics first used against them by the Boers. World War I Lawrence of Arabia and British support for the Arab uprising against the Ottoman Empire. The Ottomans were the stronger power, the Arabs the weaker. Austria-Hungary's invasion of Serbia, August 1914. Austria-Hungary was the stronger power, Serbia the weaker. Germany's invasion of Belgium, August 1914. Germany was the stronger power, Belgium the weaker. Between the World Wars Abd el-Krim led resistance in Morocco from 1920 to 1924 against French and Spanish colonial armies ten times as strong as the guerrilla force, led by General Philippe Pétain. TIGR, the first anti-fascist national-defensive organization in Europe, fought against Benito Mussolini's regime in Northeast Italy. Anglo-Irish War (Irish War of Independence) fought between the Irish Republican Army and the Black and Tans/Auxiliaries. Lloyd George (Prime Minister at the time) attempted to persuade other nations that it was not a war by refusing to use the army and using the Black and Tans instead but the conflict was conducted as an asymmetric guerrilla war and was registered as a