In 2004, Macgregor stated that he strongly supported war against Iraq. During the beginning of the Iraq War, Macgregor disagreed with those who wanted to slow the advance into Baghdad in order to fight Fedayeen paramilitary forces. In 2006, after seven retired generals criticized then Defense Secretary Donald Rumsfeld's handling of the war, Magregor faulted the generals themselves for poor war planning and the resulting complications in Iraq. In 2008, Macgregor stated he would argue that American military action in Iraq and Afghanistan "has produced very serious and negative consequences for American national-security interests". Macgregor's 2009 book, "Warrior's Rage: The Great Tank Battle of 73 Easting", argues that the failure to finish the battle with the Republican Guard in 1991 led to Iraq's second major confrontation with the United States in 2003.