War II Eastern Front military headquarters, one of several Führer Headquarters or FHQs located in various parts of Europe. The complex, built for Operation Barbarossa (the 1941 German invasion of the Soviet Union) was located in the Masurian woods, about 8 kilometres (5.0 mi) from Rastenburg, East Prussia (N/K/A Kętrzyn, Poland). It is the location where he spent much of his time during the war following the launch of Operation Barbarossa. Wunderwaffe – "silver bullet" (literally, wonder weapons), referring to weapon systems developed at the end of World War II (such as the V-1 and the V-2) that were supposed to turn around Germany's desperate situation on the battlefields. Wu-wa – mocking colloquial shortening of wunderwaffen. X X-Gerät – (X equipment) radio-navigational equipment used in German bombers. X-Zeit – (X time) zero hour Y Yellow badge – a compulsory yellow Star of David badge worn on the arm or chest to identify Jews. Z Z-Plan (or Plan Z) was the name given to the re-equipment and expansion of the Kriegsmarine (Nazi German Navy) as ordered by Adolf Hitler on 27 January 1939. The plan called for 10 battleships, four aircraft carriers, three battlecruisers, eight heavy cruisers, 44 light cruisers, 68 destroyers and 249 U-boats by 1944 that was meant to challenge the naval power of the United Kingdom. The outbreak of World War II in September 1939 came far too early to implement the plan. Zählappell – (counting roll call) a roll call used at prisons and concentration camps to account for the inmate's presence and to psychologically harass them. Zossen – The underground bunker complex that was headquarters for both the German Wehrmacht (OKW) and (Heer) Army High Command (OKH) located approximately 20 miles west of Berlin in Zossen, Germany. Zwangsarbeiter – A forced-laborer, a slave-laborer. Zwangswirtschaft – Nazi-era forced-labor or compulsion economy. Zwischenstaatliche Vertretertagungen – interstate meetings of representatives; DNSAP and NSDAP party congresses of the early years; first one held in Salzburg, Austria. Zyklon B Also spelled Cyclon B – tradename of a cyanide-based insecticide used to kill more than one million Jews, Roma, communists, and prisoners of war in Nazi gas chambers. List of abbreviations and acronymsSee the glossary above for full explanations of the terms. aA – agrarpolitischer Apparat, or Agrarian Policy Apparatus DAF – Deutsche Arbeitsfront, or German Labor Front DAK – Deutsche Afrika Korps, or German Africa Corps DAP – Deutsche Arbeiterpartei, or