During World War I, he commanded the 3rd Battalion 5th Marines and participated in numerous battles in France, earning the Navy Cross, three Silver Stars, the Croix de guerre with palm, and the French Legion of Honour.

He also oversaw the capturing of remaining guerrilla Japanese forces and contended with race rioting between white and African American sailors and Marines.

[4] Larsen joined the United States Marine Corps at the age of 23; he earned top marks in a class of 75 at Officer Candidates School.

Shortly after being field promoted to the rank of major, he led a liaison mission on June 25, 1918, during the Battle of Belleau Wood, for which he received a Citation Star.

Much of this remained similar to the naval government in place before the Japanese invasion of the island, though Larsen had increased power to change governmental organization or law by decree.

[11] A number of altercations involving the service of African American serviceman alongside whites ensued while Larsen commanded the island's forces.

It culminated in the commandeering of automatic weapons and trucks by 43 African American sailors in the short-lived Agana race riot, prompting their arrest by Marine military police and sentencing of up to four years in prison each.

[1] The medical facilities on the island were also revamped, and many of the wounded from engagements like the Battle of Iwo Jima were routed through Guam before returning home.

[16] He used the position to advocate for greater civil defense spending, accusing President Harry Truman of neglecting to fully prepare the nation for war should it come again.

[17] Lieutenant General Larsen's ribbon bar: Citation: The President of the United States of America takes pleasure in presenting the Navy Cross to Major Henry L. Larsen (MCSN: 0-540), United States Marine Corps, for exceptionally meritorious and distinguished service as Battalion Commander, Third Battalion, 5th Regiment Marines.

On 4 October 1918, Major Larsen's battalion was leading in the attack made by the Fifth Marines, while operating with the 4th French Army, east of Rheims.

The Germans repeatedly counter-attacked, in one instance directly from his left rear, and his position throughout the whole day was under a most severe artillery and machine-gun fire.

[5]Citation: The President of the United States of America takes pleasure in presenting a Gold Star in lieu of a Second Award of the Navy Cross to Major Henry L. Larsen (MCSN: 0-540), United States Marine Corps, for distinguished service in the line of his profession as Brigade Inspector, Second Brigade, U.S. Marine Corps, in Nicaragua from 1 April 1928 to 26 March 1929.

Major Larsen's duties in upbuilding and maintaining the morale of the forces, then engaged in a most difficult mission, were performed in a highly distinguished manner, always displaying zeal, activity, thorough understanding and discretion.