Andries was born the fourth son of Andries Petrus Cronjé (Graaff-Reinet, Eastern Cape, 7 April 1811 – Potchefstroom, North West, 19 September 1882) and Johanna Christina Gildenhuijsen (or Geldenhuys, Sergeants River, Swellendam, Western Cape, 22 December 1814 – Potchefstroom, 13 July 1878), who had seven sons and four daughters.

[2] Cronjé fathered 11 children, at least six daughters and four sons, including his namesake Andries Petrus Johannes, who died at the Battle of Paardeberg.

Cronjé and his men fought under the overall command of Orange Free State commander-in-chief general Philip Botha.

Andries's son and namesake was killed during a British artillery bombardment of the unfinished bridge at Vandisiedrif over the Modder River, built to rescue Piet Cronjé's troops.

[6] After the flight of the failed Boer rescuers before the British, they were scolded at by Orange Free State commander-general De Wet and general Philip Botha.

In 1903 after the war's conclusion, Cronjé with the same Piet de Wet led a deputation to visit Colonial Secretary Joseph Chamberlain in London.