U-boatU-boats were naval submarines operated by Germany, particularly in the First and Second World Wars. Although at times they were efficient fleet weapons against enemy naval warships, they were most effectively used in an economic-warfare role (commerce raiding) and enforcing a naval blockade against enemy shipping. The primary targets of the U-boat campaigns in both wars were the merchant convoys bringing supplies from Canada and other parts of the British Empire, and from the United States, to the United Kingdom and (during the Second World War) to the Soviet Union and the Allied territories in the Mediterranean.
V-1 flying bombThe V-1 flying bomb (Vergeltungswaffe 1 "Vengeance Weapon 1") was an early cruise missile. Its official Reich Aviation Ministry ( ()) designation was Fi 103. It was also known to the Allies as the buzz bomb or doodlebug and in Germany as Kirschkern (cherry stone) or Maikäfer (maybug). The V-1 was the first of the Vergeltungswaffen (V-weapons) deployed for the terror bombing of London. It was developed at Peenemünde Army Research Center in 1939 by the Luftwaffe at the beginning of the Second World War, and during initial development was known by the codename "Cherry Stone".
WarsawWarsaw, officially the Capital City of Warsaw, is the capital and largest city of Poland. The metropolis stands on the River Vistula in east-central Poland. Its population is officially estimated at 1.86 million residents within a greater metropolitan area of 3.1 million residents, which makes Warsaw the 6th most-populous city in the European Union. The city area measures and comprises 18 districts, while the metropolitan area covers . Warsaw is an alpha global city, a major cultural, political and economic hub, and the country's seat of government.