Van Rensburg and his brother Pieter were commandeered to participate in the
second Anglo-Boer War under General Sarel P. du Toit. Van Rensburg however remained unarmed and never fired a shot. His contribution was to be a stream of visions and prophesies for the duration of the war. As the seer would later explain, he believed that a nightly visitor woke him only a day before the outbreak of the war, with a message that his work was dedicated to God. On 7 December 1900,
General de Wet found himself cornered against the
Caledon River, which was in flood, while British forces were assailing his position. When his surrender appeared imminent, a message from De la Rey was delivered by a Boer scout. Van Rensburg had allegedly foreseen the situation and the message outlined an escape route, which was duly followed, leaving the pursuers to flounder in the torrent which De Wet had just traversed. De la Rey, also hard pressed by his enemy, dispatched Van Rensburg to accompany
President Steyn to Roodewal, De Wet's safe retreat in the northern Free State. Here Van Rensburg advised them to wait upon two horsemen which he described, who arrived the next day with a message from acting
President Schalk Burger.
Flight from the enemy In January 1901 Van Rensburg had a vision indicating the flight of three Boer women, who were soon found and rescued by his host Willem Bosman. President Steyn, in the company of De Wet and
Hertzog, arrived at Zendelingsfontein, De la Rey's headquarters near Klerksdorp, to consult De la Rey's physician about an eye ailment. Gaining entry to General
Kemp's war council in the bushveld region, he soon warned them against attacking a retreating enemy, which would leave them vulnerable to encirclement. At the subsequent
Battle of Hart's River on 31 March 1902, some British units did fall back, though some Canadians stood their ground until overpowered by burgher forces. Kemp, though partially or grudgingly heeding the seer's visions, was generally reluctant to give him credit. ==World War I rebellion==