Complex sentence: On 20 July 1949, the 1st Experimental Guided Missiles Group was inactivated and the unit structure was replaced by the 550th Guided Missiles Wing on the same date, which assumed the personnel and equipment of the 1st EGMG.
Split into simpler sentences: On 20 July 1949, the 1st Experimental Guided Missiles Group was inactivated and the unit structure was expanded to a Wing. It was replaced by the 550th Guided Missiles Wing on the same date, which assumed the personnel and equipment of the 1st EGMG.