From the Summary: "Iraq's chemical, biological, and nuclear weapons programs, together with Iraqi long-range missile development and support for terrorism, were the primary justifications put forward for military action. On March 17, 2003 President Bush issued an ultimatum demanding that Saddam Hussein and his sons depart from Iraq within 48 hours. On March 19, offensive operations began with air strikes against Iraqi leadership positions. By April 15, after 27 days of operations, coalition forces were in relative control of all major Iraqi cities and Iraqi political and military leadership had disintegrated. On May 1, President Bush declared an end to major combat operations. There was no use of chemical or biological (CB) weapons, and no CB weapons stockpiles have been found."
CRS Report for Congress, RL31701