The 105th Infantry traces its origins to the 2nd New York Volunteer Infantry Regiment. It was an infantry regiment that served in the Union Army during the American Civil War. It is also known as the Troy Regiment. The regiment was organized in Troy, New York and was mustered in for a two-year enlistment on 14 May 1861. The regiment suffered 26 deaths from wounds and 22 from other causes, for a total of 48 fatalities. The regiment was mustered out of service on 26 May 1863. On 17 May 1898, the 2nd New York Infantry was reformed for service in the Spanish-American War. The 2nd New York was supposed to join the U.S. forces in Cuba, but was kept in the States because of an initial lack of transport ships and then because of an outbreak of Typhoid among the soldiers already serving in Cuba. Nevertheless, the 2nd Regiment lost 32 men, all to disease.
The 2nd New York was mustered up again for the Border War in 1916, and was thus prepared for when the US Army mobilized for the First World War in April 1917. The 2nd New York was redesignated as the 105th Infantry Regiment and was assigned to the 53rd Brigade of the 27th Infantry Division. Serving with the 105th in the 53rd Brigade was the 106th Infantry Regiment. At the beginning of the war, the 105th had a strength of 2,720 officers and men. The regiment shipped out for France in May 1918, and upon arrival, was sent to the East Poperinghe Line with the rest of the 27th Division. On 25 July 1918, the 105th rotated into the frontline to relieve elements of the British 6th Division. German offensives in the spring of 1918 had penetrated deep into the allied lines, and created salients near Amiens and Hazebrouck. On 31 August 1918, the Ypres-Lys Offensive began in order to force the Germans out from the Dickebusch/Scherpenberg area, and thus reduce the Amiens salient. The assault began with the 105th on the left side of the advance (abreast with the 106th Infantry), and fighting continued for a few days until the regiment was relieved by the British 41st Division. The Second Somme Offensive began on 24 September 1918 and concluded on 21 October 1918. Its main objective was piercing the Hindenburg Line, an intricate system of German defenses with an average depth of six to eight kilometers. On 27 September, elements of the 105th moved forward in support of an attack by the 106th Regiment. The two regiments of the 53rd Brigade made moderate gains near Guillemont, but were thrown back by a German counterattack. It was here, near Ronssoy, that 1LT William B. Turner earned the Medal of Honor. On 27 September 1918, 1LT Turner was leading his men in an attack, under terrific artillery and machine-gun fire, after they had become separated from the rest of the company in the darkness. He singlehandedly charged enemy machine-gun positions and led his men through three lines of trenches. He managed to capture a fourth and final trench-line, but was killed when the Germans counterattacked. On 29 September, the 105th attempted to capture a formidable German strongpoint known as "The Knoll," but the New Yorkers were halted by savage amounts of machine-gun fire that rained down from the elevated German positions. On 1 October, the entire 27th Division was moved to Prémont to serve with the II Corps and helped spearhead an assault against the German defenses on 17 October 1918. The regiment swiftly captured a portion of the enemy line at L’Arbe de Guise, holding it against powerful German counterattacks. The following day, 18 October, the 105th was on the offensive again, advancing on one of the primary north-south German lines before being halted by strong resistance. On 19 October, the regiment again advanced from their forward positions, this time in the face of only slight opposition, and easily took the main German works. The 105th remained in combat for a few more days before the entire division was relieved on 21 October 1918. By 19 March 1919, the regiment had returned in full to the United States where it was quickly mustered out. During its combat action in the First World War, the 105th Infantry Regiment suffered 1,609 casualties including 1,284 wounded, 253 killed, and 72 who later died of their wounds.
While Germany and Fascist Italy were in the process of conquering most of Europe in 1939 and 1940, and the Empire of Japan was grabbing territory in the Pacific and China, the United States felt unprepared in the event war was necessary to combat the Axis Powers and began mobilizing its army in response. The Selective Training and Service Act of 1940, which allowed the government to draft US citizens, was passed, and all available National Guard Divisions were inducted into Federal Service within a year. The 105th Infantry Regiment was mustered for federal service and assigned to the 27th Infantry Division on 15 October 1940. The Regiment was organized into twelve companies, which initially drew their membership from a number of towns in the capital region. Companies A, C, and D were recruited from Troy. Company B was recruited from Cohoes. Companies E, F, and H were recruited from Schenectady. Companies G, I, K, L, and M were recruited from Amsterdam, Malone, Glens Falls, Saratoga Springs, and Gloversville respectively. Additional regimental troops came from Hoosick Falls, Whitehall, and Saranac Lake. The regiment moved to Fort McClellan, Alabama after it was inducted, and then to Hawaii on 17 March 1942, after the Attack on Pearl Harbor. There, they trained for combat in the Pacific Theater against the Imperial Japanese Army.
The 105th Infantry Regiment earned its "baptism by fire" on Butaritari Island on 20 November 1943. Here, during the Battle of Makin, the 3rd Battalion (3-105) made an assault landing alongside the 165th Infantry Regiment. It formed a "Special Landings Group", which preceded the main landing craft in Amtracs and cleared the beaches for the subsequent landing waves. As the landing craft approached the beach, they began to receive small-arms and machine-gun fire from the island's defenders. The assault troops were also surprised to discover that even though they were approaching the beach at high tide as planned, a miscalculation of the lagoon's depth caused their small boats to go aground, forcing them to walk the final 250 yards (230 m) to the beach in waist-deep water. Equipment and weapons were lost or water-soaked, but only three men were killed approaching the beach, mainly because the defenders chose to make their final stand farther inland along the tank barriers. 3-105 fought with the 165th Infantry for the remainder of the battle, which lasted 4 days and cost the Americans 66 killed and 185 wounded. On 24 November 1943, the entire regiment left the atoll for Hawaii, where they arrived on 2 December 1943.
The Regiment left Hawaii on May 31 and landed on Saipan on 17 June 1944, where it fought with the rest of the 27th Division for the first time. Also fighting on Saipan were the 2nd and 4th Marine Divisions. The 105th Regiment began the campaign by clearing the hilly and well fortified southern point of Saipan, which was later found to have been held by over 1,200 Japanese defenders.Early on 18 June, the regiment assisted the 165th Infantry Regiment with clearing the island's southern airfield, Aslito Airfield, and took up defensive positions that night on the east of the field. On 19 June, 1-105 advanced on Nafutan Point under the command of LTC William J. O'Brien but became bogged down, and despite armored support and flanking maneuvers, the Japanese position was too strong. 1-105 was unable to breach the Japanese defenses at Nafutan point by 21 June, and were ordered to move north in order to press the advance, and 2-105 was slated with reducing the Nafutan position. At this point of the battle, the three American divisions moved north abreast of each other; the 2nd Marine Division advanced up the west coast, the 4th Marine Division advanced up the east coast, and the 27th Infantry Division advanced up the center of the island. At Nafutan Point, the 1,200 remaining Japanese attacked the 600 men of 2-105, but they were defeated when 3-105 arrived to help, and Nafutan was finally declared secure on 27 June. Meanwhile, on 23 June 1944, the units of the 27th Division advanced up what the soldiers called "Death Valley" and "Purple Heart Ridge" toward Mount Tapotchau. The enemy was dug in to the caves along the cliffs, and units of the 27th moving through the valley, including the 105th Infantry Regiment, were subjected to deadly and accurate enemy fire. The soldiers were forced to advance through thick jungle at the opening of a plateau onto a flat plain where the Japanese held the high ground on both sides. Elements of the 165th Infantry and 1-105 joined with elements of the 23rd Marine Regiment to capture the villages of Donnay and Hasigoru from 26–27 June. This high ground, known as "Obie's Ridge," was held by the 105th against repeated Japanese counterattacks.
30 June was the beginning of the end of the Saipan battle. The Japanese began moving north toward Marpi Point, and this was to be their last stand. On 1 July, the 4th Marine Division advanced both north and east toward Marpi Point, the 2nd Marine Division marched up the west coast toward Tanapag, and the 27th Division, along with the 105th Regiment, continued to attack up the center of the island. 1-105 was occupying Obie's Ridge when it was ordered to move up to 3-105's poisition and link up with the left flank of the 165th Infantry, and the right flank of the 106th Infantry, however, this required crossing 1,700 yards of open terrain. On 2 July, 1-105 marched at double time across the open ground and dug in at their objective. On 4 July, the 105th had secured Flores Point, and 2-105, which had been fighting at Nafutan Point, rejoined the regiment. The regiment attacked up the Tanapag Plain until they were roughly 1,200 yards south of Makunshka. This action on the Tanapag Plain has been studied by the United States Army Center of Military History and is well documented. Here, 1-105 dug in on the east side of a railroad track that ran north-south about 150 yards west of the beach near the Tanapag plain. 2-105 was dug in to the west of the railroad, but there was a considerable gap between the battalion, so LTC O'Brien concentrated his battalion's anti-tank weapons and machine-guns near the divide.During the evening and night of 6 July, the Japanese launched minor probing attacks against the 105th's lines to find weak points, and at 0445 on 7 July, they launched the largest Banzai charge of the war; it is estimated over 4,000 Japanese took part in the charge simultaneously. MAJ Edward McCarthy, then in command of 2-105 and one of the few officers of the regiment to survive the attack, described the scene as follows: "It reminded me of one of those old cattle-stampede scenes of the movies. The camera is in a hole in the ground and you see the herd coming and they leap up and over you and are gone. Only the Japs just kept coming and coming. I didn’t think they’d ever stop". This charge hit the 105th directly and violently, and the two lead battalions were overrun. LTC O'Brien led the defense in the 1-105 area, with a pistol in each hand and even manning a nearby .50 Caliber machine-gun until he was killed. When his body was found, there were 30 dead Japanese around him, and he received a posthumous Medal of Honor. When the carnage of the final charge finally ended, 2,295 dead Japanese lay in front of the 105th's positions, and another 2,016 lay intermingled or in the rear of the 105th's positions for a total of 4,311 dead. US casualties were also heavy, and 1-105 and 2-105 suffered 406 KIA and 512 WIA. In 1-105, Lieutenant John Mulhearn of B Co was the only surviving officer, and in 2-105, all the company commanders and the entire battalion staff were killed, but the battalion commander (MAJ McCarthy) survived. During the fighting on 7 July, Private Thomas Baker fought with the Japanese although seriously wounded early in the attack, he refused to be evacuated and continued to fight in the close-range battle until running out of ammunition. When a comrade was wounded while trying to carry him to safety, Baker insisted that he be left behind. At his request, his comrades left him propped against a tree and gave him a pistol, which had eight bullets remaining. When American forces retook the position, they found the pistol, then empty, and eight dead Japanese soldiers around Baker's body. PVT Baker received a posthumous Medal of Honor. CPT Ben L. Salomon was the 105th's regimental dentist officer but on Saipan he was quickly needed as a surgeon. Salomon's aid station was set up only 50 yards behind the forward foxhole line on 7 July. Fighting was heavy and the Japanese assault soon overran the perimeter, then the aid station. Salomon was able to kill the enemy that entered the hospital tent and ordered the wounded to be evacuated, while he stayed to cover their withdrawal. When an Army team returned to the site days later, Salomon's body was found slumped over a machine gun, with the bodies of 98 enemy troops piled up in front of his position. His body had 76 bullet wounds and many bayonet wounds, up to 24 of which may have been received while he was still alive. CPT Salomon eventually received the Medal of Honor in 2002, and it is believed that the long delay was due to discriminatory practices arising from Salomon's Jewish faith. The fighting on 7 July decimated the regiment, and the memory of that night would define the character of the survivors, and set forth a courageous tradition for the future. The badly mauled 105th continued operations on Saipan against an enemy that was all but used up, and the island was eventually declared secure on 9 July 1944.
Once the Battle of Saipan was completed, the 105th Infantry Regiment was assigned to garrison the island from 15–30 July. They then moved to Espiritu Santo for some much needed R&R on 4 September. The regiment had slowly begun refilling its ranks with replacement officers and men, but were definitely still understrength and weary by the time they departed for Okinawa on 25 March 1945. 3-105 was a little better off than their two sister battalions, so they were selected to assault the island of Tsugen Shima. In this engagement, on 10 April 1945, the Japanese lost 243 men killed while thirty escaped, and the Americans lost fourteen dead. These would be the opening shots of the 105th's involvement in Operation Iceberg. The 105th landed on Okinawa on 12 April, and moved to the south where they confronted the Shuri Line. The 27th Infantry Division comprised the XXIV Corps' western flank, and the 105th attacked the Japanese strongpoint at Kakazu Ridge, but the attack faltered. Here in southern Okinawa, the 105th was mired in mud, torrential rainfall, and static warfare reminiscent of the First World War. After pitched fighting across the Shuri Line, the exhausted 27th Infantry Division was relieved by the 1st Marine Division. According to one Marine veteran who relieved his Army compatriots; "Boy, they looked like hell coming off that line." After suffering heavy casualties at Okinawa, the beleaguered men of the 105th arrived in Japan on 12 September 1945 to serve a garrison role, and the regiment was disbanded on 12 December 1945 when it returned home to the United States.