Complex sentence: Most of their service was in the Apache Wars of the 1870s to 1890s though the last scouts retired in 1947, where they were the eyes and ears of the United States military and sometimes the cultural translators for the various Apache bands and the Americans.
Split into simpler sentences: Most of their service was in the Apache Wars of the 1870s to 1890s though the last scouts retired in 1947. The scouts were the eyes and ears of the United States military and sometimes the cultural translators for the various Apache bands and the Americans.