[5] Fourie was born as one of the eight children of Christiaan Ernst Fourie (Grahamstown, South Africa, 14 June 1815 – Blauwkop District, Ermelo, South Africa, 11 March 1897) and Catharina Hendriena Lucasina Espach (Plaas (Farm) Goedehoop, Grahamstown, 12 February 1820 – Plaas Valharts, Ermelo, 24 August 1886).

Joachim Fourie grew up in Lydenburg, married Aletta Elizabeth de Clercq (Transvaal, 20 June 1849 – Carolina, 5 July 1902) and had four sons and one daughter by her.

He distinguished himself and although he then lacked a military rank was elected in March 1900 Assistant General (Vechtgeneraal).

Fourie replaced Schalk Burger and led the Commandos from the districts of Carolina, Lydenburg, Heidelberg (including Boksburg), Standerton and Soutpansberg but could not stem the northward advance of British general Redvers Buller and his troops.

[6] Fourie fought several battles, including at Modderspruit (Afrikaans: Slag van die Twee Riviere (Battle of the two rivers), 28 November 1899), Spion Kop (Spioenkop, 23–24 January 1900), and Witrand - Dalmanutha (Bergendal, 21–27 August 1900).