Urban Warfare
Urban warfare is warfare conducted in urban areas such as towns and cities. Generally defined as areas of large built up structures and civilian populations.Warfare conducted in population centres before the 20th century is generally considered siege warfare since it usually involved the moving of armies en mass to lay seige to cities, or the meeting of two armies on a neutral battlefield, such as the Battle of Hastings in 1066.
This tactic was used for over a 1000 years, and featured in many wars of the ancient world, in particular the crusades.
Urban combat is very different from combat in the open at both the operational and tactical level. A complicating factor of urban warfare is the presence of large concentrations of civilians, either innocent bystanders or sometimes as combatants ranging from armed militias and gangs to individuals defending their homes.
Tactics are complicated by limited fields of view and fire because of buildings, enhanced concealment and cover for defenders, and the ease of placement of booby traps and snipers.
Tactics
The characteristics of an average city include tall buildings, narrow alleys, sewage tunnels and possibly a subway system.
The buildings can provide excellent sniping posts while alleys and rubble-filled streets are ideal for planting booby traps.
Defenders can move from one part of the city to another undetected using underground tunnels and spring ambushes.
Meanwhile, the attackers tend to become more exposed than the defender as they must use the open streets more often, unfamiliar with the defenders' secret and hidden routes. During a house to house search the attacker is often also exposed on the streets.
Usually, defenders will only use urban warfare as a last resort, and generally try to fight the enemy away from major population centres. Urban warfare threatens the civilian population, industry, and infrastructure, of which the purpose of a defensive army is to generally protect. Urban warfare is generally forced upon the weaker side of a conflict that desperately needs defensibility, risking the destruction if the defensive forces were deployed elsewhere.