He fought in Venetian service during the siege of Candia and the Morean War, and helped to establish the Bavarian army and commanded it during the battle of Vienna.

[5] Hannibal's five brothers followed their father's military career, two of them dying on the battlefield; three of them also entered the service of Venice in the Cretan War.

[3] In 1681 Degenfeld entered the service of the Electorate of Bavaria, rising quickly to the rank of field marshal lieutenant and president of the Aulic War Council by 1682.

[7][8] He played a crucial role in the reforms that resulted in the establishment of a standing Bavarian Army under Elector Maximilian II Emanuel.

[17] In 1683 Degenfeld commanded the Bavarian forces sent to the relief of the Ottoman siege of Vienna, though nominally headed by Elector Maximilian Emanuel himself.

[8][18][19] After the relief of Vienna, and as a result of perceived slights from the elector, who now viewed himself as a war leader on his own account, Degenfeld requested to be released from Bavarian service, which was granted on 12 October.

He assumed command of the Venetian forces in the Morea and led them in the capture of the castle of Zarnata and in the subsequent Battle of Kalamata, where he defeated the Ottomans under the Kapudan Pasha.

However, after the death of Königsmarck and Girolamo Corner of disease, and the ascent of Morosini to the dogeship, Degenfeld was recalled to service as captain-general in spring 1691.