Henry V succeeded as ruling Prince of Wolfenbüttel when his father was killed in a 1514 battle during the Saxon feud. He soon entered into the Great Diocesan Feud with the Prince-Bishopric of Hildesheim under John IV of Saxe-Lauenburg, against whom he lost the Battle of Soltau in 1519. However, the duke profited from his support of Charles V in the succession as Holy Roman Emperor, and in 1523 the Bishopric had to cede large territories to Wolfenbüttel. Henry remained loyal to the Imperial authority during the German Peasants' War, and in 1528 he assisted Emperor Charles V in the War of the League of Cognac against King Francis I of France in Italy.