Complex sentence: During World War II, New Denver became a Japanese-Canadian internment camp, not long after the attack on Pearl Harbour in December of 1941, men between 18 and 45 were sent to labour camps in Eastern Canada.
Split into simpler sentences: During World War II, New Denver became a Japanese-Canadian internment camp. Not long after the attack on Pearl Harbour in December of 1941 men between 18 and 45 were sent to labour camps in Eastern Canada.