The smallest independent land unit is the division, although brigades such as engineers, artillery, or armoured cars can be attached to these. On sea, units are either single capital ships or flotillas of small ships such as destroyers. For the air force, the unit is a Wing or Group, depending on nationality. Land divisions include infantry, cavalry, and tanks. Land brigades include anti-tank guns, anti-aircraft artillery and military police. On the map the player can direct divisions or groups of divisions. Fighting starts when an army starts moving into a defended enemy territory. The invading units do not have to be inside enemy territory to attack. A province is immediately occupied when the invaders arrive there with no opposition left. Because of this, a player can blitz through large swaths of enemy lands with minimal micromanagement. In addition, units who move constantly lose organization and risk losing supply, so poorly executed attempts to blitzkrieg can be stopped. Provinces can be fortified and infrastructure increased to improve combat performance. Structures include radar, and static AA. Many fortifications are pre-built, such as the Maginot Line along the French-German border. Air units include bombers, fighters and transports. These divisions can, depending on type, engage in tactical or strategic missions. Sea units include transports, aircraft carriers, battleships, cruisers, destroyers, and submarines. Each unit has a strength, speed, and effective engagement range. Naval combats simulate the range between fleets, allowing only units in range to fire. This can make naval combats tactically complex. Controversy and censorship Like its predecessor Hearts of Iron, the game is banned in the People's Republic of China. The main point of contention seems to be that the game portrays the various Chinese warlords as independent entities, while according to the PRC government they were nominally part of the Republic of China governed by the Chinese Nationalist government, represented in-game as 'Nationalist China'. Also, the Tibetan flag used in-game is banned in China. Paradox has stated that it will not reduce the level of historical accuracy in order to appease the PRC censors. Anachronistically, Germany is represented with the flag of the German Empire as used by Germany until 1935, and not the Swastika flag, as was also done in the earlier board game Axis & Allies. Laws in Germany prohibit the use of the swastika. Additionally, in the German version of the game, pictures of leading Nazi leaders, such as