Complex sentence: Henrietta Secondary School was founded as "Henrietta School" in 1924 and was known by that name until 1941 when was closed down due to the Japanese occupation of Hong Kong.
Split into simpler sentences: Henrietta Secondary School was founded as "Henrietta School" in 1924 and was known by that name until 1941. In 1941, it was closed down due to the Japanese occupation of Hong Kong.