Complex sentence: Among the western European Jews deported to the camp were 456 Jews from Denmark, sent to Theresienstadt in 1943, and a number of European Jewish children whom Danish organizations had tried to conceal in foster homes.
Split into simpler sentences: Among the western European Jews deported to the camp were 456 Jews from Denmark, sent to Theresienstadt in 1943. Included also in the transports were European Jewish children whom Danish organisations had tried to conceal in foster homes.