In the second relief of Mantua, Sebottendorf led a 4,086-man division down the Brenta River valley. He participated in the Battle of Bassano, after which his division "was reduced to only one and a third battalions, four and a half companies, and two squadrons." He subsequently joined Wurmser in a dash for Mantua. The bulk of the Austrians reached the fortress intact, but Sebottendorf and his soldiers were cooped up in Mantua for the duration of the long siege, during which many of the men died.