He is particularly remembered for his establishment of a new settlement for traders on the banks of the Alster near the Neue Burg in Hamburg.

He accompanied him on his expedition against Philipp von Heinsberg, Archbishop of Cologne, fought at the Battle of Halerfeld on 1 August 1180 (to the north-west of Osnabrück) at the side of Count Bernhard I of Ratzeburg, when he received from Henry the Lion the decisive rights in the region of the Middle Weser which formed the basis of the County of Schauenburg.

In 1196, he went to the Holy Land for the second time for the Crusade of Henry VI, he then returned home in 1198.

The reign of Adolf III coincided with Denmark's attempts at expansion under Kings Canute VI and his brother and successor Valdemar II.

After Adolf lost the Battle of Stellau in 1201 and was later taken prisoner in Hamburg by Valdemar, this expansion was successful for some decades.