Complex sentence: One of them was'in disguise' until 1943-well into World War II. This harbouring of Jewish people on Lenz and Kraus' behalf brought with it the significant danger of being pilloried as a sympathizer.
Split into simpler sentences: One of them was'in disguise' until 1943-well into WWII. This habouring of Jewish people on Lenz and Kraus' behalf brought with it the significant danger of being pilloried as a sympathizer.