George, after taking a religious profession in his youth, returned briefly to the world, but in 1454 reverted to holy orders and later became Bishop of Metz.

Jacob I was the opposite of his father; Enea Silvio de Piccolomini (Pope Pius II) characterized him as famous among the Germans for his justice and intelligence.

When as the result of a miscarriage his sister Agnes fled in the middle of a conflict about inheritance, the Margrave lost his claim to the Duchy of Schleswig.

In 1442 he bought for 30,000 guilders from the descendants of Walter von Geroldseck half the lordship of Lahr and Mahlberg.

Jakob married 25 July 1418 Catherine,[1] daughter of Charles II, Duke of Lorraine and Margaret of the Palatinate.