[4] Wilson fought in the Second Boer War as a corporal in the 2nd Queensland Mounted Infantry Contingent, serving in the advance to Johannesburg and Pretoria, the Battle of Diamond Hill and other actions.

Following the evacuation of Allied forces to Egypt, in April 1916 he led the advance of the Anzac Mounted Division across the Suez Canal when the Turks attacked near Romani.

In the Second Battle of the Jordan (30 April – 4 May 1918) he seized Es Salt with astonishing speed and, when the Turks counter-attacked, succeeded in withdrawing his brigade from a perilous situation.

Forty miles (64 km) behind the Turkish lines after the breakthrough at Megiddo (20 September), Wilson's brigade advanced southwards on Jenin, capturing three or four times their own number.

On 1 October Wilson changed the course of the battle for Damascus by boldly directing his brigade through the city at dawn, leaving thousands of Turks cut off while his regiments pressed up the road to Homs.

He was shy in manner and very sparing of speech, but his quiet figure concealed the spirit of a great master of horse, and between the time of his promotion to brigadier and his dramatic, unpremeditated dash through Damascus as the vanguard of the British and Arab Armies a year later, he became marked as a leader capable of handling a command far more important than a brigade."