[1] His father was Jacques Philippe de Croÿ-Roeulx (1614–1685), a descendant of Jean III of Croy-Roeulx, son of Antoine le Grand.

Croÿ joined the Danish army during the Scanian War and was first a volunteer officer but was relatively quickly made a colonel for his bravery.

In November of that same year, he had recovered from his injuries and was nominated governor of the city of Landskrona which was the main Danish stronghold during the entire war.

[2] Later on, he fought with success in the Habsburg Imperial army against the Ottoman Turks and participated in both the liberation of Vienna in 1683 and the attack on Belgrade in 1690.

On demand of his creditors, his body, which rested at St. Nicholas Church, was not buried for more than 190 years, and, when mummified, was exhibited as a curiosity.