In May 1809, the rebels captured Sjenica. They repulsed an Ottoman attack on the village of Suvodol in early June, and seized Novi Pazar later that month, but failed to take its fortress. Minor clashes also took place in the north of Kosovo. Lacking numbers and adequate military training, the rebels failed to establish a corridor to Montenegro and gain access to the Adriatic Sea, which Karađorđe had described as one of his key aims. The rebels experienced further setbacks in Niš, where 3,000 were surrounded at Čegar Hill in May–June 1809. Knowing that he and his men would be impaled if captured, rebel commander Stevan Sinđelić fired at his entrenchment's gun powder magazine, setting off a massive explosion that killed him and everyone else in the vicinity. On the site of the battle, the Ottoman commander Hurshid Pasha built a stone tower with the skulls of Sinđelić and his fighters embedded in its walls as a warning to others who wished to rebel.