Schmelt labor camps and had been deemed unfit for work. According to Christopher Browning, transports of Jews unfit for work were sent to the gas chamber at Auschwitz from autumn 1941. The evidence for this and the February 1942 transport was contested in 2015 by Nikolaus Wachsmann. Around 20 March 1942, according to Danuta Czech, a transport of Polish Jews from Silesia and Zagłębie Dąbrowskie was taken straight from the station to the Auschwitz II gas chamber, which had just come into operation. On 26 and 28 March, two transports of Slovakian Jews were registered as prisoners in the women's camp, where they were kept for slave labour; these were the first transports organized by Adolf Eichmann's department IV B4 (the Jewish office) in the Reich Security Head Office (RSHA). On 30 March the first RHSA transport arrived from France. "Selection", where new arrivals were chosen for work or the gas chamber, began in April 1942 and was conducted regularly from July. Piper writes that this reflected Germany's increasing need for labor. Those selected as unfit for work were gassed without being registered as prisoners. There is also disagreement about how many were gassed in Auschwitz I. Perry Broad, an SS-Unterscharführer, wrote that "transport after transport vanished in the Auschwitz [I] crematorium." In the view of Filip Müller, one of the Auschwitz I Sonderkommando, tens of thousands of Jews were murdered there from France, Holland, Slovakia, Upper Silesia, and Yugoslavia, and from the Theresienstadt, Ciechanow, and Grodno ghettos. Against this, Jean-Claude Pressac estimated that up to 10,000 people had been murdered in Auschwitz I. The last inmates gassed there, in December 1942, were around 400 members of the Auschwitz II Sonderkommando, who had been forced to dig up and burn the remains of that camp's mass graves, thought to hold over 100,000 corpses. Auschwitz II-Birkenau Construction After visiting Auschwitz I in March 1941, it appears that Himmler ordered that the camp be expanded, although Peter Hayes notes that, on 10 January 1941, the Polish underground told the Polish government-in-exile in London: "the Auschwitz concentration camp ...can accommodate approximately 7,000 prisoners at present, and is to be rebuilt to hold approximately 30,000." Construction of Auschwitz II-Birkenau—called a Kriegsgefangenenlager (prisoner-of-war camp) on blueprints—began in October 1941 in Brzezinka, about three kilometers from Auschwitz I. The initial plan was that Auschwitz II would consist of four sectors (Bauabschnitte I–IV), each consisting of six