His Grand Tour took William Henry to the court of Louis XV in France, among other places.

After his mother's death, his brother Charles acted as regent until William Henry came of age in 1741.

In 1742 he sold his regiment to the Landgrave of Hesse-Darmstadt, during his stay in Frankfurt on the occasion of the coronation of Charles VII.

He often traveled to Paris, where he received military honors—as was usual at the time for ruling nobility—including a promotion to field marshal.

Noteworthy buildings from this periods are the Saarbrücken Castle, the Louis Church and Basilica of St. John.

The downside of his magnificent city was an immense debt, which his son and successor Louis had to deal with.

William Henry and his princely contemporaries show the possibilities and limits of an enlightened absolutist policy.

As much as he insisted on enlightened principles of legal reforms, continued economic stimulus and the exercise of religious tolerance, he also remained a patriarchal ruler who forbade his subjects to actively participate in government and who tried to regulate all areas of life with an immense flood of regulations, and who suppressed social protests harshly.