The 3rd contingent, 100 strong, commanded by Captain S Gran Hubbe, sailed on the Maplemore from Adelaide upon 7th March 1900, and landed at Beira on 11th April. They formed part of General Carrington's force which crossed Rhodesia and entered the Transvaal from about Mafeking.
It was intended that the 2nd Regiment of the Rhodesian Field Force should consist of the 3rd South Australians, 3rd Tasmanians, and the 3rd Queenslanders; but before Mafeking was reached, on 24th June, the regiment was split up and was never brought together. Between 4th July and 9th August the squadron was patrolling the Marico and working towards Elands River district (see Rhodesia Regiment). On 6th August Lieutenant Collins was wounded. On the 9th the squadron retired to Mafeking with Carrington. On 13th August they had a skirmish. Next day they were in a sharp fight at Buffelshoek. On the 15th the squadron was put into a Composite Bushmen Regiment, along with 'D' Squadron of the 1st New South Wales Bushmen, Captain Poison's squadron of the 5th New Zealand, and the 3rd Tasmanians. For a long time the regiment did excellent work in the Western Transvaal as part of Lord Methuen's force. At Buffelshoek on the 21st of that month the South Australians had sharp fighting and suffered casualties. For a second time they were in action at Ottoshoop, on 12th September, when Captain Gran Hubbe was killed, and the squadron suffered other losses. At Lichtenburg on the 26th of the same month they again had casualties. Lieutenant Collins having recovered, he was appointed to command the contingent with the rank of Captain.
Throughout the latter part of 1900 and the first quarter of 1901 the Composite Bushmen Regiment was in many engagements, chiefly in the Western Transvaal, but also in the north of the Orange River Colony. In several of these the enemy fought with considerable determination, and as a matter of course losses were frequent. For many months the Western Transvaal was dangerously denuded of troops, and consequently the strain on those who were there was severe. The most constant watchfulness was necessary, for the enemy was ever alert and was ably led. At Uitvalskop, on 3rd February 1901, the squadron lost 1 man killed and Lieutenant J T Dempsey and 5 men wounded; and in the very severely contested action near Hartebeestfontein, on 16th February, Captain Collins, for the second time, and 1 man were wounded. Altogether the squadron had 4 killed and 20 wounded.
In April the squadron left Lord Methuen's force for home, and he wrote to the Secretary of the South Australian Bushmen's Committee a letter, in which he "tendered his tribute of praise" for the splendid work performed by the squadron,—their cheerfulness in hardship, and good discipline. Among other things, his Lordship said, "I cannot conceive any body of men of whom a commander has greater reason to be proud".