1939. The change was never fully implemented, as the Länder were still used as administrative divisions for some government departments such as education. Oppression of churches Main article: Kirchenkampf See also: Religion in Nazi Germany When the Nazis seized power in 1933, roughly 67 percent of the population of Germany was Protestant, 33 percent was Roman Catholic, while Jews made up less than 1 percent. Grand Admiral Erich Raeder had advised Hitler in June that air superiority was a pre-condition for a successful invasion of Britain, so Hitler ordered a series of aerial attacks on Royal Air Force (RAF) airbases and radar stations, as well as nightly air raids. Marinus van der Lubbe, a Dutch communist, was found guilty of starting the blaze. See Statistisches Jahrbuch 2006. As part of a general public health campaign, water supplies were cleaned up, lead and mercury were removed from consumer products, and women were urged to undergo regular screenings for breast cancer.