Olmütz was well defended, and the siege was slow and difficult. Frederick hoped to provoke an Austrian counter-attack, but Daun chose to avoid direct engagements with the Prussian force, focusing instead on harassing its supply lines. By late June the city's defences were badly damaged, but the besieging army's supplies were acutely low. On 30 June Austrian forces commanded by General Ernst von Laudon intercepted a massive supply convoy from Silesia bound for the Prussian army at Olmütz and destroyed it in the Battle of Domstadtl. After this loss, the Prussians were forced to break off the siege and withdraw from Moravia, abandoning their final major invasion of Austrian territory during the war.