Complex sentence: In 1729, he travelled to Kuči where he met with Radonja Petrović in his attempt to mobilize Brda ("the Highlands") against the Ottomans.
Split into simpler sentences: In 1729, he travelled to Kuči. He met with Radonja Petrović with whom he sought to mobilize Brda ("the Highlands") against the Ottomans.