...US Marines-Iraqi National Guards cordons thrown up around Shiite city - one external, second enclosing Old City where fighting rages around Imam Ali Mosque...
A "double cordon" is called a "contravallation" and was first used by Julius Caesar. It serves a double purpose. It both prevents a breakout in force from the besieged area, but more importantly, it prevents a break-in from outsiders trying to relieve the siege. If you recall, the "siege" of Fallujah was partially broken with convoys of supplies and fighters coming in from outside. The Marines aren't going to let *that* happen again. |