Born in Killybrackey, near Dungannon, County Tyrone on 10 July 1914 into a family of cattle breeders. His father, Joseph Donnelly sold his farm in 1917 and the family moved to Dundalk and opened a greengrocer's shop. Joseph Donnelly became quite prosperous, running his shop, dealing cattle and buying and selling property in the Dundalk area. In addition to Charles, the Donnellys had five other sons and two daughters. Charles' mother, Rose, died in 1927, when he was 13 years old.