Marines run for cover from Iraqi fire in the port of Umm-Qasr in southern Iraq (news - web sites), March 23, 2003 as they met pockets of resistance from Republican Guards in a residential area beside the port. Iraqi troops and paramilitary fighters loyal to President Saddam Hussein (news - web sites) held up a U.S. advance toward Baghdad on Sunday, inflicting casualties and taking American prisoners on the fourth day of war.