In early 1900, under Ridley's 4th Mounted Infantry Brigade, the Unit joined the British advance from the Modder River to Bloemfontein. This march included the Battle of Poplar Grove on 7 March in which Lieutenant Freislich was killed. A few weeks later, the Unit participated in an action at Thaba Nchu under General Ian Hamilton an event related in Winston Churchill's "Ian Hamilton's March". Churchill observed "...our loses in this smart action were about twenty killed and wounded, among whom were no less than 5 officers" of Marshall's Horse. They also fought at Israel's Poort on 25 April 1900. Captain Gethin (pictured below) was killed that day. Marshall himself was wounded, to be replaced as Commanding Officer by Captain Corbett (Somersetshire Light Infantry). Lord Roberts mentioned their performance in his dispatches.