Complex sentence: The 1st Dragoons was reformed in the Vietnam era as 1st Squadron, 1st U.S. Cavalry, and continues to this day in the Iraqi War as the oldest cavalry unit, as well as the most decorated unit, in the U.S. Army.
Split into simpler sentences: The 1st Dragoons was reformed in the Vietnam era as the 1st Squadron, 1st U.S. Cavalry. It has served in the Iraqi War and remains as the oldest cavalry unit, as well as the most decorated one, in the U.S. Army.