Donat John Heissler was born in the Holy Roman Empire in about 1648, at the end of the Thirty Years' War.

He enlisted in the service of the Habsburgs at a very young age, and as a cavalry captain, Heissler obtained the rank of knight on 15 September 1678.

On 16 September 1685, he was promoted to the rank of general and in his first expedition prevented the conquering of Munkács and Ofen, and defeated the Turks at Szeged.

On 9 February 1692, immediately after his release, he was promoted to the rank of General of the Cavalry and proved that his courage had not been affected by his imprisonment, by seizing the town of Oradea on 5 June.

He was elevated to the rank of Count, a title he kept until he died on 1 September 1696 from the consequences of a wound he received 5 days before in the Battle of Ulaş near Timișoara.

Francis Joseph had also a brilliant career as a member of the Geheimrat then as royal judge of the Land from 1732, to finally become governor of Moravia in 1740. second son of the count, led from 1705 the Regiment founded by Donat John.