Complex sentence: Most British troops defending the settlement had been withdrawn earlier in the year and George's position was not a strong one and he served until the Japanese declaration of war and seizure of the Shanghai International Settlement in December 1941.
Split into simpler sentences: Most British troops defending the settlement had been withdrawn earlier in the year and George's position was not a strong one. George served until the Japanese declaration of war and seizure of the Shanghai International Settlement in December 1941.