bunkers, surrounded by ring of barbed wire and ground defensive positions connected by tunnels. A couple of observation points were set up on platforms in the oak trees surrounding the pine forest. The area was surrounded by a defensive strip of bunkers, anti-aircraft guns and tanks, as well as anti-tank ditches and minefields. There was a tea house, a barber shop, a bathhouse, a sauna, a cinema and a swimming pool, primarily intended for Hitler who never used it. The facility also contained a large vegetable garden organised by the German horticultural company Zeidenspiner to provide Hitler with a secure supply of food. Hitler's personal chef selected his vegetables and the food was chemically analyzed before being tried by a taster because of Hitler's fear of poisoning. Oxygen tanks were also available at Hitler's insistence. Water for the site was provided by artesian wells while power was provided by a generator. Some historians, including Lloyd Clark, indicate that some buildings were connected by tunnels. The bunkers were constructed by Organisation Todt using some local Ukrainian workers, forced labour but mainly Soviet prisoners of war. The code name for the secret construction project was Anlage Eichenhain (Camp Oak Grove). The 4000 forced laborers were lined up and shot when construction was finished. The complex was served by a daily three-hour flight connection from Berlin to the airfield in Kalinovka from the compound. There was also a regular train connection from Berlin-Charlottenburg to "Eichenbein" station at Werwolf. The journey took 34 hours. During Germany's Eastern campaign, Adolf Hitler lived mainly at FHQ Wolfsschanze (near Rastenburg, East Prussia) but he stayed at FHQ Werwolf three times: 16 July to 30 October 1942: The weather was hot, up to , and the bunkers were humid. Hitler caught severe influenza, with a temperature running up to . In this condition, he gave his fateful Führer Directive 45, splitting Army Group South into two parts in a bid to reach both Stalingrad and the Caucasus oil fields simultaneously. The Directive was the main cause of the eventual defeat and destruction of the German 6th Army at Stalingrad and the German Army's subsequent withdrawal from Southern Russia to a new front near the Soviet city of Kursk. 19 February to 13 March 1943: to observe Field Marshal Erich von Manstein's Kharkhov offensive in the wake of Germany's defeat at Stalingrad. 27 August to 15 September 1943: to