Complex sentence: Campioni's staff was headquartered in the Palace of the Grand Master of the Knights of Rhodes; his Chief of Staff was brigadier general Roberto Sequi, while he was in turn subordinate to the command of Army Group East, based in Tirana.
Split into simpler sentences: Campioni's staff was headquartered in the Palace of the Grand Master of the Knights of Rhodes; his Chief of Staff was Brigadier General Roberto Sequi. The Rhodes HQ was subordinate to the command of Army Group East, based in Tirana.