BAGHDAD, Iraq, Dec. 23 — When Maj. Gen. Graeme Lamb, a 50-year-old Briton, arrived in June to lead the mainly European force controlling southeastern Iraq, he was skeptical, he said. He felt that "this is going to be a lot more difficult than we realized." But as General Lamb prepared to hand his command to another British general, he said at a news conference here on Tuesday that Saddam Hussein's capture and other changes, including progress in restoring oil installations, power stations and running water, as well as the Iraqis' fast-rising prosperity, had fostered a new confidence that the American-led...