Complex sentence: His family lived at several outposts in the Arizona and New Mexico Territories, wherever his father happened to be stationed, until December 1882 when they finally settled at Vancouver Barracks in the Washington Territory.
Split into simpler sentences: His family lived at several outposts in the Arizona and New Mexico Territories, wherever his father happened to be stationed. In December 1882, they finally settled at Vancouver Barracks in the Washington Territory.