In the First World War he fought for the Union of South Africa against the German Empire, and then was an officer in the British Army, commanding several battalions.

At the age of 17, while visiting his father in Pretoria, at the start of the Second Boer War, the Field-Cornet's office said he was too young to fight and refused to enlist him.

He and one of his brothers then joined the Boer forces "by virtue of having thrown our belongings through a carriage window and climbing aboard".

During the initial phase of the War, he fought several battles, including the engagement at Surprise Hill (Vaalkop) and in the Boer victory at Spionkop.

After a string of Boer defeats in set-piece warfare and the British capture of Pretoria, Reitz was one of the fighters who remained in the field.

He joined General Smuts who decided to conduct guerrilla operations, not in the territories of the Boer republics, but in the Cape Colony.

A fierce fight, subsequently to be known as the Battle of Elands River, took place, with the Lancers being caught in a cross-fire and suffering heavy casualties.

[2] In his book Commando, Reitz recounts how Lord Vivian pointed out his bivouac tent and told him it would be worth his while to take a look at it.

He reports that "nothing could have proved more clearly how nearly the Boer cause was spent than these starving, ragged men clad in skins or sacking, their bodies covered in sores, from lack of salt or food, and their appearance was a great shock to us, who came from the better-conditioned forces in the Cape."

Reitz's father was among the signatories of the surrender, but only in his official capacity; he refused to sign himself and was given two weeks to settle his affairs in Pretoria before leaving the country.

He left for Madagascar with his brother, where they eked out a living convoying goods by ox-transport "hard work in dank fever-stricken forests and across mountains sodden with eternal rain".

He is buried south of Mariepskop, approximately 10 km (6.2 mi) east of the Blyde River Canyon in Mpumalanga.