carbon monoxide in the bunkers of Fort VII, including children as well as women whom the authorities classified as Polish prostitutes. Other Owińska hospital patients were gassed in sealed trucks using exhaust fumes. The same method was utilized in the Kochanówka hospital near Łódz, where 840 persons were murdered in 1940, totalling 1,126 victims in 286 clinics. This was the first "successful" test of the mass murder of Poles using gas. This technique was later perfected on many other psychiatric patients in Poland and in Germany; starting in 1941, the technique was widely employed in the extermination camps. Nazi gas vans were also first used in 1940 to murder mentally ill Polish children. In 1943, the SS and Police Leader in Poland, Wilhelm Koppe, ordered more than 30,000 Polish patients with tuberculosis to be exterminated as the so-called "health hazard" to the General Government. They were murdered mostly at the Chełmno extermination camp. Persecution of the Catholic Church Sir Ian Kershaw wrote that, in Hitler's scheme for the Germanization of Central and Eastern Europe, there would be no place for the Christian Churches. Historically, the church had been a leading force in Polish nationalism against foreign domination, thus the Nazis targeted clergy, monks and nuns in their terror campaigns—both for their resistance activity and their cultural importance. Of the brief period of military control from 1 September 193925 October 1939, Davies wrote: "according to one source, 714 mass executions were carried out, and 6,376 people, mainly Catholics, were shot. Other put the death toll in one town alone at 20,000. It was a taste of things to come." According to the Encyclopædia Britannica, 1,811 Polish priests were murdered in Nazi concentration camps. Nazi policy towards the Church was at its most severe in the territories it annexed to Greater Germany, where the Nazis set about systematically dismantling the Church – arresting its leaders, exiling its clergymen, closing its churches, monasteries and convents. Many clergymen were murdered. The Catholic Church was suppressed in the annexed territory of Reichsgau Wartheland more harshly than elsewhere. In the Wartheland, regional leader Arthur Greiser, with the encouragement of Reinhard Heydrich and Martin Bormann, launched a severe attack on the Catholic Church. Its properties and funds were confiscated, and lay organisations shut down. Evans wrote that "Numerous clergy, monks, diocesan administrators and officials of the Church were arrested, deported to the General Government, taken off to