Complex sentence: Munch possessed 1006 of his paintings when he died in 1944, in which all of them he gave as a testamentary gift to Oslo Municipality when he wrote down his will on the 18th of April 1940, right after the Germans had occupied Norway.
Split into simpler sentences: Munch possessed 1006 of his paintings when he died in 1944. He gave all these paintings as a testamentary gift to the municipality of Oslo when he wrote down his will on the 18th of April 1940, right after the Germans had occupied Norway.