Johan Wilhelm (aka Wilhelm Johann) Heilig was the youngest son of a footballing and cycling family from Kleinton, near Toowoomba. His father had moved from Ludwigsburg in Germany in 1893, marrying another German emigree in Henrietta Kolberg. Johan’s uncle moved his family from Germany to the Toowoomba region in 1889. Heilig’s mother died in 1900, and his father in 1904, and it appears he and his siblings grew up in the household of their uncle. Several members of the combined family played for Southern Rovers in the Toowoomba league around 1911.
Heilig enlisted in August 1916, and joined the 26th Battalion, fighting at Ypres, Villers Bretonneux, Passchendaele and the Somme. He suffered with trench fever in 1918, leading to a return to England and was subsequently attached to general staff until he returned to Australia in late 1919.
In 1918, his name was added to the Toowoomba British Football Association honour board. He was living in Ipswich by 1925 and anglicised his name to John Williams Heilig. He died on the 7th of December, 1962 in Ipswich.