Complex sentence: German and Italian attacks in Operation Sonnenblume forced the Allies into a precipitate retreat to the Egyptian border, except for a garrison left behind at Tobruk, pending reorganisation and a counter-offensive.
Split into simpler sentences: German and Italian attacks in Operation Sonnenblume forced the Allies into a precipitate retreat to the Egyptian border. A garrison was left behind at Tobruk, pending reorganisation and a counter-offensive.