Complex sentence: A first effort failed, but on 25 August 1799 Hohenwart and at least four other people, including the brothers Klotz, reached-again-the Kleinglockner, where they installed a summit cross (one of the main goals of the church expedition).
Split into simpler sentences: A first effort failed, but on August 25,1799 the brothers Klotz and at least 4 other people reached-again-the Kleinglockner. There they installed a cross (one of the main goals of the church expedition).