Complex sentence: Italy sided with Nazi Germany during World War II and initially enjoyed successes; however, Allied forces eventually captured Italian overseas colonies and by the time Italy itself was invaded in 1943, its empire had all but ceased to exist.
Split into simpler sentences: Italy sided with Nazi Germany during World War II and initially enjoyed successes. However, Allied forces eventually captured Italian overseas colonies and by the time Italy itself was invaded in 1943, its empire had all but ceased to exist.