Complex sentence: He was the first Austroamerican, which marched into the Innviertel on 4 May 1945 with the 86th division of the 3rd US Army at Burghausen, where he stayed at the Brauerei Schnaitl.
Split into simpler sentences: He was the first Austroamerican, which marched into the Innviertel on 4 May 1945 with the 86. US-army at Burghausen, where he stayed at the Brauerei Schnaitl.