158th Infantry Regiment (158th IR)
158th Regimental Combat Team (158th RCT) "Bushmasters"
U.S. Army

Background
The 158th Infantry Regiment (158th IR) was unit of the Arizona National Guard assigned to the 45th Infantry Division (45th ID). Their motto was “Cuidado" (Take Care). On September 16, 1940 ordered into Federal service in the U.S. Army and began training at Fort Sill in Oklahoma then moved to Camp Barkeley in Texas. During February 1941 participated in maneuvers in Louisiana.

Wartime History
On December 8, 1941 when the United States entered World War II, detached from the 45th Division and sent to Panama arriving January 2, 1942 as part of the Panama Mobile Force to defend the Canal Zone (CZ) and trained in jungle warfare. In Panama, adopted the nickname "Bushmasters" for the Bushmaster venomous snake. On February 11, 1942 relieved from the 45th Division when it became a triangular division and instead became a separate infantry regiment. The 158th became one of four infantry regiments of the Panama Mobile Force to create and train a jungle platoon using specialized equipment and tactics. During November 1942, prepared to transfer to Australia.

In late January 1943 arrives Brisbane. In the middle of March shipped in echelons to Port Moresby in New Guinea. In late May 1943 moves to Milne Bay. On June 20, 1943 the 2nd Battalion provides security for the 6th Army Headquarters. On June 24, 1943 the first elements of the 158th, less the 2nd battalion land without opposition on Kiriwina Island. On June 30, 1943 at dawn the rest of the regiment lands and occupies Kiriwina and Woodlark to provide security. In the middle of July 1943 the 2nd Battalion moves to Goodenough Island as a security force. On October 21, 1943 when the 6th Army Headquarters moves to the island, resumes security duty. On December 15, 1943 Company G departs for Arawe on western New Britain and is later joined by the entire 2nd Battalion and enters combat. Afterwards, the entire 158th assembles at Finschafen. Redesignated as the 158th Regimental Combat Team (158th RCT) with the 147th Field Artillery Battalion.

During May 1944, deploys to Toem in western New Guinea and relieves the 163rd RCT on the Tor River and was ordered to capture Sarmi Airfield near Sarmi in their first significant combat engagement against the Japanese Army 36th Division. During the Battle of Lone Tree Hill, the 158th suffers 70 killed, 257 wounded, and 4 missing. The 158th killed an estimated 920 Japanese and took 11 prisoners. On June 14, 1944 relieved to prepared for their next operation.

Damortis-Rosario Road Campaign
On January 9, 1945 during the U.S. Army landing at Lingayen Gulf, the 158th RCT was held in reserve in the I Corps area. On January 11, 1945 the 158th lands as part of the Sixth Army reserve. On January 12, 1945 late in the day, released from army reserve and attached to the 43rd Infanty Division (43rd ID) to secure Highway 3 and Highway 11 and open the road from Damortis to Rosario. That same day, they advance to Rabon and relieves elements of 172nd Infantry Regiment (172nd IR) and begins patrolling as far as Damortis to close a gap in the line between the ??? Infantry Regiment and 172d Infantry Regiment.

On January 13, 1945 the 158th liberates Damortis without a struggle. On January 14, 1945 the RCT 158 advances eastward toward Rosario but meets such heavy fire in defile near Amlang that it pulls back approximately to its starting line with 20 killed and 65 wounded. The day is dubbed "Bloody Sunday" by the 158th. On January 15, 1945 the 158th assisted by artillery, naval gunfire, and aircraft, begins clearing the defile near Amlang.

On January 17, 1945 the 63d Inf is attached to 158th to help clear heights commanding Damortis-Rosario Road in the Amlang-Cataguintingan region. That same day the 158th takes a ridge about 1,000 yards northeast of Damortis. On January 21, 1945 the 158th and 63d Regts finish clearing Blue Ridge near Amlang and afterwards 63d Inf is withdrawn into corps reserve. By January 23, 1945 Company G, captured two 305mm Howitzer Type 7 (1918) and killed 164 enemy. For this action, Company G earned the Presidential Unit Citation.

On Jauary 24, 1945 the 43rd Division regroups for a coordinated effort scheduled to commence the next day to clear the heights dominating road in the Pozorrubio-Sison-Rosario-Camp One area. The RCT 158 and 172d Inf are designated as the MacNider Force under the command of Brigadier General Hanford MacNider. That same day, elements of 158th begin assault on ridge northwest of Cataguintingan but the Japanese are firmly entrenched on the ridge. On January 25, 1945 the 158th continues efforts to gain ridge northwest of Cataguintingan. On January 26, 1945 the 158th finishes clearing ridge northwest of Cataguintingan. On January 27, 1945 the Damortis-Rosario road is opened with link up of 172d and RCT 158 at Cataguintingan. On February 1, 1945 the 158th consolidates on hills and ridges commanding Damortis-Rosario-Pozorrubio road. On February 13, 1945 the 158th is relieved by 33d Division and withdraws from the frontlines. On February 15, 1945 the 158th arrives in Tarlac in army reserve to rest and regroup for the remainder of the month.

Batangas Campaign
On March 4, 1945 the 158th and 11th Airborne Division are tasked with clearing Balayan Bay and Batangas Bay on southern Luzon. On March 5, 1945 the 158th is releases from reserve for assignment to XIV Corps. That same day, the 158 drives east along Route 17 on Balayan Bay until stopped by opposition near Langanan. On March 6, 1945 elements of 158th reach Lemery across Pansipit River from Taal. On March 7, 1945 the 158th advances through undefended Taal and gains several miles to the east and south, completing first phase of attack. On March 8, 1945 the 158th mops up and patrols. On March 10, 1945 3d Bn, 158th gets into position to attack toward the Calumpan Peninsula. On March 11, 1945 the 2d Battalion, 158th Infantry clears Batangas and immediate vicinity while rest of regiment is cleaning out the region to the west and northwest. That same day, the 158th is assigned to the upcoming assault on Legaspi. On March 17, 1945 in Batangas, relieved by the 11th Airborne DIvision, 188th Infantry Regiment, less one battalion. On March 30, 1945 the 158th assembles at Lemery were they are embarked aboard transports in Balayan Bay for the upcoming invasion of Legaspi.

Bicol Campaign
On April 1, 1945 the Legaspi Attack Group (TG 78.4) after aerial and naval bombardment lands the RCT 158, reinf, at Rawis in Legaspi meeting only token opposition on the beach and quickly secures Legaspi and Legaspi Airfield and Libog. Ashore, General Hanford MacNider takes command. Considerable opposition develops inland when the 2d Bn encounters resistance near Daraga.

On April 2, 1945 the RCT 158 develops defense position in the Legaspi area. 1st Bn is halted by fire from Bantog. 2d withdraws through Daraga after relieving elements isolated near there. On April 3, 1945 the RCT 158 makes limited progress against enemy positions on a ridge (Estanza Hills) south of Daraga. On April 4, 1945 1st Bn of RCT 158, moving northward to positions northwest of Busay, attacks southward along a ridge on left flank while 2d and 3d Bns attack frontally south of Daraga. Progress for next week is very slow since enemy must be destroyed in detail. On April 6, 1945 1st Bn continues southward along ridge to trail running west from Daraga, about a mile south of Busay. 2d Bn reaches Route 160, which extends from Legaspi to Daraga. Meanwhile, AT Co, reinf, in shore-to-shore operation to clear Sorsogon Province is transported from Legaspi and lands unapposed at Bacon, and advances overland to Sorsogon. On April 7, 1945 the 158th continues efforts to extend control over the Legaspi area.

On April 8, 1945 patrols of AT Co, RCT 158, reach Bulan on west coast of Bicol Peninsula and request reinforcements to attack. On April 9, 1945 the 158th overcomes resistance near Daraga and secures the junction of Highway 1 and Highway 160. Meanwhile, widespread patrolling in Sorsogon Province indicates that Japanese are now concealed in hills around San Francisco, roughly 5 miles northeast of Bulan.

On April 10, 1945 the 158th, after securing Legaspi area, begins reconnaissance of islands in Albay Gulf and prepares to send elements to aid AT Co in the San Francisco area. On April 11, 1945 in the afternoon, one column of 158th moves by truck to Malabog and then marches into Camalig which is undefended while another column moves to the southwest slopes of Tagaytay Ridge.

On April 12, 1945 1st Battalion and 3d Battalion, 158th begin a two-pronged assault against the Cituinan Hills, which enemy is defending stubbornly. Meanwhile, the 2d Bn, understrength is trucked south along Route 1 to Bulan area to clear the San Francisco region of Sorsogon Province.

On April 13, 1945 1st Battalion and 3d Battalion, 158th continues indecisive battle for Cituinan Hills area for next week. Meanwhile, 2d Bn, reinf by AT Co, attacks toward San Francisco in Sorsogon Province meeting heavy fire from hills around the town. On April 14, 1945 the 2d Bn of RCT 158 continues attack toward San Francisco after air strikes but makes little headway. Meanwhile, Co I moves up Route 1 to Iriga. Rest of regt is held up to north but probes northward. On April 15, 1945 the main body of RCT 158 continues almost futile attacks on Cituinan Hills from north and south. I and R Platoon drives N on Route 27. 2d Bn makes two-pronged assault on San Francisco and takes the town. On April 16, 1945 2d Bn after repulsing determined counterattack on San Francisco, attacks and clears the entire area clearning the southern tip of Bicol Peninsula. On April 18, 1945 the 158th attacking Cituinan Hills from north and south are 2,000 yards apart. Meanwhile, the 2d Bn, having turned over responsibility for mopping up Sorsogon Province to guerrillas, moves into position near Malabog to attack Cituinan Hill from the east. On April 19, 1945 the entire 158th attacks Cituinan Hills from three directions for the next week, progressing slowly but methodically with aid of aircraft and artillery. On April 22, 1945 attack to clear Cituinan Hills continues to progress slowly. On April 27, 1945 the 1st Battalion and 3d Battalion make contact on main ridge of Cituinan Hills. On April 28, 1945 Japanese resistance in Cituinan Hills collapses. On April 29, 1945 the 158th leaves the 3d Bn to mop up stragglers in Camalig area then advances northward. 1st Bn advances along Route 1 to Pauili River while 2d Bn, reinf by AT Co moves along Route 27.

On May 1, 1945 the 1st Bn, reaches Anayan at the junction of Highway 1 and Highway 27, without opposition. 3d Bn is ordered to establish contact with 2d Bn, which is advancing west on Route 27. The 5th Cav of 1st Cav Div, pushing southeast into the Bicol Region is attached to RCT 158. On May 3, 1945 the 158th probes the Mount Isarog area to locate and destroy enemy remnants in the Bicol Region.

On June 15, 1945 the 158th prepares to conduct operations in northern Luzon as directed by Eighth Army and remains in the Philippines until the end of the Pacific War. The 158th was selected to participate in Operation Downfall, and was to be part of Operation Olympic and assault Tanegashima two days before the main invasion of Kyūshū and Shikoku scheduled for November 1, 1945. During World War II, the 158th suffered more than 1,400 casaulties.

Postwar
On October 13, 1945, the 158th arrives in Yokohama as part of the U.S. occupation force in Japan. On January 17, 1946 inactivated in Utsunomiya in Japan.

On February 18, 1947 the 158th Infantry was reorganized in the Arizona National Guard headquartered in Tucson. On March 1, 1959 reorganized under the U.S. Army Combat Arms Regimental System to consist of the 1st and 2nd Battle Groups. On March 1, 1963 redesignated as the 1st, 2nd, and 3rd Battalions.

On December 10, 1967, the 158th Infantry was broken up and converted to other units. The 1st Battalion became the 1581st Military Police Battalion, the 2nd Battalion became the Headquarters and Headquarters Detachment, 1120th Transportation Battalion, the 2220th Transportation Company, and the 2221st Transportation Company, and the 3rd Battalion became the Headquarters and Headquarters Company, 1583d Military Police Battalion and the 1154th-1156th Military Police Companies.

Awards
Philippine Presidential Unit Citation

Commanding Officers (C.O.)
Colonel J. Prugh Herndon
Brigadier General Hanford MacNider (August 6, 1944–August 1945)

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