20 years ago, units from San Diego were among the first in Iraq.

Twenty years ago on Monday, the first US troops entered Iraq, and navies off the coast flew sorties and fired guided missiles. The war will be declared a victory in just a few weeks before the fighting intensifies amid a strong insurgency.

Violence will reign in Iraq for more than a decade.

The Iraq invasion strategy, called “Shock and Awe” by the military planners of the George W. Bush administration, was led by many military units based in San Diego. On March 20, 2003, more than 20,000 Marines and sailors under the command of the 1st Marine Expeditionary Force, based at Camp Pendleton, and its infantry unit, the 1st Marine Division, entered Iraq across the Kuwait border.

The Marines released a video on Monday acknowledging these forces.

San Diego-based warships, including the USS Constellation, launched airstrikes and guided missiles across the country.

According to an April 2003 USAF report, all combined coalition forces in the region numbered over 466,000 troops.

The report details the extent of the invasion. From March 20 to April 30, over 1,800 coalition aircraft flew over 41,000 sorties in Iraq. 30% of all personnel of the US armed forces were involved.

In just 26 days, the coalition achieved its tactical goal. The Iraqi army was defeated and Saddam Hussein was overthrown. However, the dissolution of Hussein’s army and political party sowed the seeds of an insurgency that escalated into violence over the next decade.

The Bush administration and Pentagon leaders in the months leading up to the invasion sounded the alarm about Iraq’s military capabilities and its readiness to use weapons of mass destruction. Some have tried to link the Hussein regime to the 9/11 attacks.

Greg Daddis, director of the Center for War and Society and USS Midway Chair in Modern Military History at San Diego State University. Daddis, a West Point graduate, was serving in Iraq when the US first went to war in the country during the Gulf War in 1991.

According to him, the US and its allies entered Iraq based on a number of false assumptions.

“(We assumed) we would bring democracy to Iraq,” Daddis said. “That we will change Iraqi society and politics (and) that the war will be easy – it will end quickly. We assumed that this would be the second part of Desert Storm, and it is clear that these assumptions did not materialize.

Nearly 4,500 US military personnel have been killed in Iraq, and the death toll of Iraqis, including civilians, has been estimated at between 150,000 and over 500,000.

For Daddis, the main lesson of the Iraq war is that there are limits to what the US can achieve with military force abroad.

“As we move forward as a nation, I think we should have these uncomfortable conversations and more honest conversations about our faith in war and the limits of what we can achieve when we go to war,” he said. Daddis. “I think (this is) something we should be thinking about as we look back at this 20th anniversary so we don’t make the same mistakes in the future.”