Open city

In war, in the event of the imminent capture of a city, the government/military structure of the nation that controls the city will sometimes declare it an open city, thus announcing that it has abandoned all defensive efforts. The attacking armies of the opposing military will then be expected not to bomb or otherwise attack the city but simply march in. The concept aims at protecting the city's historic landmarks and resident civilians from an unnecessary battle.

Attacking forces do not always respect the declaration of an "open city". Defensive forces will use it as a political tactic as well. In some cases, the declaration of a city to be "open" is made by a side on the verge of defeat and surrender; in other cases, those making such a declaration are willing and able to fight on but prefer that the specific city be spared.

According to the of the Geneva Conventions, it is forbidden for the attacking party to "attack, by any means whatsoever, non-defended localities".

Several cities were declared open during World War II:

In 1977, a far left group in Japan called the "National Open City Declaration Movement Network" began organizing activists to make cities preemptively declare themselves "defenseless" under the Geneva Convention, so that in the event of war, they would be legally forced to welcome any invasion. This is rejected by nearly all of Japan's political parties and the ruling government as inherently absurd, since Japan is not in a war, and in the event of war such a decision would have to be approved by the national government. However, the Social Democratic Party which was the junior party of the ruling coalition from 1994 to 1996 supported it.

Nevertheless, four wards of Tokyo and Kagoshima City, Japan's southernmost port, among many other cities, are considering legislation to be declared "open cities".

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Wikipedia