Born in 1711 at Schnabelweyd as Karl Sigmund, he was raised in a strict household with ten brothers and sisters. He entered the Benedictine Order in 1730 receiving the name Heinrich. He studied philosophy, theology, and law. Six years later he traveled to Rome.
In 1759 immediately after his selection as Prince Bishop and Abbot of Fulda, he had to flee his realm as it was overrun by both the French and the Hessens in the Seven Year War. Finally, with peace in 1763, he undertook the rebuilding of Fulda and its economy. Rising at 4 am each morning, he was an energetic and enlightened ruler. With currency, reform came sound money. He built roads, bridges, housing, churches, and orphanages. He improved the spa at Brückenau, had the land surveyed for minerals, and founded the porcelain works which became famous. The porcelain works was disbanded shortly after his death.
He provided freedom of religion, forbidding mistreatment of Jews and employed Protestants alongside Catholics in his administration. Along with libraries around the land, he introduced a general school system which was one of the best of his time.