The Goslar mines for centuries had been a thorn in the side of the Dukes of Brunswick-Wolfenbüttel ruling over the adjacent Harz estates. In 1552 - after decades of legal proceedings, feuds and skirmishing - Duke Henry V took the occasion of the city's weakened position upon the Schmalkaldic War and seized ownership of the mines from the citizens. Mining operations were further promoted by Henry's son and successor Duke Julius of Brunswick-Wolfenbüttel from 1568. During the Thirty Years' War the Goslar citizens once again tried to regain the Rammelsberg mines distinguishing themselves as loyal supporters of the Imperial forces against the Protestant commander Christian the Younger of Brunswick; however, to no avail as his nephew Duke Augustus the Younger reconciled with Emperor Ferdinand in 1642. Under the Welf dukes, gold was also won from the 18th century onwards.