At Del Mar Beach on Camp Pendleton, a Marine Corps brass band played jazz standards while thousands of Marines and sailors wearing camouflage mingled under the bright midday sun.
The event, "From Sea to Shore, an Amphibious Assault Demonstration," began at noon and runs the rest of the afternoon.
The demonstration includes firing artillery from a base beach into the base's firing ranges, the Marines said.
"Marines will fire 155 mm high-explosive rounds from M777 howitzers," the Marines said in a statement Thursday. "The M777 will fire into designated ranges with all safety precautions in place."
Outside the base, Interstate 5 sits quiet — devoid of traffic after an early-morning decision to close the freeway for four hours during the event.
Vice President JD Vance headlines a series of Trump administration officials scheduled to speak.
Defense Secretary Pete Hegseth and Navy Secretary John Phelan will also address the crowd of thousands of uniformed service members.
The Commandant of the Marine Corps, Gen. Eric M. Smith will also speak.
The artillery demonstration riled Rep. Mike Levin, D-San Juan Capistrano, who said it poses a safety risk.
"Unfortunately, reports confirming that artillery will be fired over Interstate 5 — requiring full freeway and rail closures — have caused understandable frustration throughout the surrounding community," Levin said in a statement Saturday. "These actions pose unnecessary safety risks and significant disruptions for residents, businesses and first responders."
