Complex sentence: The Ariane class were a sub-class of the 600 Series submarines, made by France in the interwar period, most of which served during World War Two, except for the the "Ondine", who sank on its test trial due to collision in 1928.
Split into simpler sentences: The Ariane class were a sub-class of the 600 Series submarines, made by France in the interwar period. Most of them served during World War Two, except for the the "Ondine", who sank on its test trial due to collision in 1928.