Only one month after the 69th Infantry Regiment returned to New York from its Mexican Border Campaign on March 7, 1917, the United States Congress approved President Woodrow Wilson’s appeal for a declaration of war against Germany on April 6th. On July 25, 1917, the 69th was mustered into Federal service and re-designated the 165th Infantry.  On August 5, 1917, the War Department created the 42nd Division comprised of National Guard units from 26 states and the District of Columbia, and selected the 165th as one of its four infantry regiments.  At the time, Major Douglas MacArthur, who had been instrumental in forming the new Division, said: "The 42nd Division stretches like a Rainbow from one end of America to the other.”  The name stuck, and it became known as the 42nd “Rainbow” Division. 

            To reach wartime strength of 3,600 officers and men, the 165th Infantry received transfers from the 7th, 12th, 14th, 23rd, and 71st New York National Guard regiments, and recruiters enthusiastically canvassed Manhattan for volunteers.  On August 20, 1917, soldiers of the 165th left their armory on Lexington Avenue and East 25th Street and traveled to Camp Albert L. Mills near Garden City, Long Island.     

            After two months of fundamental rifle and bayonet training, drilling, and lots of strenuous physical activities, the 165th began leaving Camp Mills on October 25th when the 1st Battalion left by train for Montreal where it boarded the transport ship Tunisia.  On the night of October 29th, the rest of the Regiment went to Hoboken, New Jersey to board the transport ship America, a former German luxury liner, confiscated by the United States in April 1917 and converted to an American troop ship.   

The 165th Infantry arrived in southern England and Brest, France by November 12, one of the first units of the American Expeditionary Force (AEF) to land in Europe.  From there, the regiment left for training at Valcouleurs in northeast France, travelling by train aboard “Quarante et Huit’s” or “40 and 8’s,” French railroad cars designed to transport forty men or eight horses.  Billeted in the homes and barns of nearby townspeople, the 165th underwent intensive training in trench warfare including marksmanship, bayonet drill, trench construction, and climbing out of the trench to attack the enemy’s position—“going over the top.”

            On December 26, 1917, the 165th left Valcouleurs to travel through the Vosges Mountains 80 miles east to Longeau and Luneville, a legendary march in the history of the Rainbow Division known as the Valley Forge Hike.  A blizzard that began on Christmas Eve left snow three feet deep on the mountain roads and temperatures plummeted below zero.  Over four days, many soldiers’ hob nail boots wore out, and they suffered from frost bite and blistered and bloodied feet that left scarlet trails through the snow.  Supply wagons could not keep up or became stuck so soldiers had nothing to eat at night.  Joyce Kilmer noted how after the march, “The men had aged twenty years.  But their hearts were unchanged.”

            After two months of additional training, the 165th entered the trenches at the Rouges Bouquet Chaussilles Sector on February 26, 1918, conducting mostly defensive operations against the Germans’ relentless artillery, gas, and infantry attacks.  Tragedy struck on March 7 when German artillery landed on the roof of a dugout which buried a group of soldiers of Company E beneath tons of dirt, mud, and shattered timbers.  After hours of intense rescue efforts, still under heavy fire, two men were rescued and five bodies were recovered.  The remaining 18 soldiers were entombed in the collapsed dugout.  Sgt. Joyce Kilmer, a renowned poet, wrote the poem “Rouge Bouquet” to memorialize the men who died and Fr. Duffy first read it aloud that St. Patrick’s Day at a graveside ceremony.

            By the end of March 1918, the 165th moved to Baccarat where it honed its skills and maneuverability with numerous patrols and trench raids resulting in dozens of captured      German soldiers and positions.  On June 18, the regiment moved to the Champagne sector near St. Hillaire and beginning on July 14, the 165th and rest of the Rainbow Division stopped a major German offensive in the Second Battle of the Marne.  By July 18, the 165th led a vigorous counterattack that pushed the German line three miles east.

As the Germans retreated, the Allies launched the Aisne-Marne Offensive and beginning July 26, the battle-hardened 165th Infantry led the attack across the Ourcq River where the Germans had established a defensive position on the north side.  Crossing an open field in the face of German artillery and machine gun fire, the 165th successfully crossed the Ourcq and forced a German withdrawal.  But after four days of intense fighting, the regiment suffered nearly 1,400 casualties—42% of the unit, including 264 KIAs. 

            After the Battle of the Ourcq River, the 165th moved to Goncourt where it rested, received 600 replacements and pursued rigorous combat training in preparation for the Allied Meuse-Argonne Offensive.  Towards the end of the campaign, the 165th was in the vanguard of the 42nd Division’s and US First Army’s drive to take city of Sedan, suffering heavy casualties on November 7, while capturing Hill 252 that overlooked the Meuse River.  After the Armistice on November 11, 1918, the 165th Infantry served occupation duty in Remagen before returning to New York in April 1919. 

After eight months in the trenches, the men of the 165^th Infantry established an impressive wartime record.   Living up to its nickname, the Fighting 69th spent 164 days in combat in some of the most significant campaigns of the war, had more than 2,500 casualties including nearly 900 deaths, and earned sixty Distinguished Service Crosses and three Medals of Honor.