Question: Which Argentine leftist terrorist group tried to seize the barracks of the 29th Forest Infantry regiment?

Context paragraphs:
Highland Light Infantry of Canada: The Highland Light Infantry of Canada was an infantry regiment of the Canadian Army.  Founded in 1886 as the 29th Waterloo Battalion of Infantry it went through several name changes including, in 1900, the 29th Waterloo Regiment and in 1915, the 29th Regiment (Highland Light Infantry of Canada).  It acquired its present title in 1920.  In 1954, as a result of the Kennedy Report on the Reserve Army, this regiment was amalgamated with The Perth Regiment to form The Perth and Waterloo Regiment (Highland Light Infantry of Canada).  However, this amalgamation was undone in 1957 and the Highland Light Infantry of Canada resumed its regimental identity.  In 1965 it amalgamated with the Scots Fusiliers of Canada and was renamed the Highland Fusiliers of Canada.

52nd Infantry Division (German Empire): The 52nd Infantry Division ("52.Infanterie-Division") was a division of the Imperial German Army during World War I.  The division was formed on March 6, 1915, from units taken from other divisions or newly raised.  The division was initially mixed, with two infantry regiments from the Grand Duchy of Baden, one infantry regiment from Prussian Saxony, and Prussian and Baden support units (cavalry, artillery, engineers, and service and support units).  While the infantry regiments and the divisional cavalry squadron were regular army units, the rest of the division was made up of reserve units and units formed during the war.  The 66th Magdeburg Infantry Regiment was taken from the 7th Infantry Division, and the 169th and 170th Infantry Regiments were taken from Baden's 29th Infantry Division.  The 52nd Infantry Division became more Baden as the war progressed, as the 66th Magdeburg Infantry Regiment, the regiment from Prussian Saxony, was replaced on April 6, 1917, by Baden's 111th Infantry Regiment "Margrave Ludwig Wilhelm".

37th Arkansas Infantry Regiment: The 37th Arkansas Infantry Regiment was organized in Pope County by individual companies during March through June 1862 and organized as the 29th Arkansas Infantry Regiment upon its acceptance into Confederate service on June 6, 1862, under the command of Colonel Joseph C. Pleasants.  The unit was also at one time designated as the 1st Trans-Mississippi Infantry Regiment.  The unit's Field Officers were Lieutenant Colonel Jeptha C. Johnson and Major John A. Geoghegan.  It was renamed as the 37th Arkansas Infantry regiment following the Battle of Prairie Grove.  The unit was composed of volunteer companies from the following counties:

115th Infantry Regiment (United States): The 115th Infantry Regiment, Maryland Army National Guard was an infantry regiment of the United States Army.  It traced its roots back to the American Revolutionary War, although its official U.S. Army lineage begins in 1881.  The units to which the 115th Regiment claims lineage served in the Revolutionary War and the Civil War, but the 115th itself was only credited with service in World War I, World War II, and the Global War on Terror.  Prior to the reorganization into the 58th Brigade Combat Team, the 1–115th was part of the Third Brigade, 29th Infantry Division (Light).  In 2006, the 115th was consolidated (merged) with the 175th Infantry Regiment.  As a result of this consolidation, it no longer exists as a separate regiment.

18th Arkansas Infantry Regiment (Marmaduke's): The 18th Arkansas Infantry (Marmaduke's) (1861–1865) was a Confederate Army infantry regiment during the American Civil War.  The unit was also briefly identified as the 1st Arkansas Infantry Battalion.  The unit was most often referred to as the 3rd Confederate Infantry Regiment.  The designation "Confederate Infantry Regiment" was intended to convey the difference between Provisional Confederate Army units and Regular Confederate Army Units, with Provisional units being those regiments who received a state designation such as "XX Arkansas Infantry Regiment".  In practice, the designation was most often utilized when Regiments were assembled utilizing companies from more than one confederate state.  The "3rd Confederate Infantry Regiment" is occasionally misidentified as the 3rd Arkansas Infantry Regiment commanded by Colonel Van H. Manning.

Montoneros: Montoneros (Spanish: "Movimiento Peronista Montonero-MPM" ) was an Argentine leftist terrorist and urban guerrilla group, active during the 1960s and 1970s.  The name is an allusion to the 19th century cavalry militias, called Montoneras, who fought for the Partido Federal during the Argentine Civil Wars.

39th Arkansas Infantry Regiment: The 39th Arkansas Infantry Regiment or Cocke's Arkansas Infantry Regiment (also known as "Johnson's regiment," "Hawthorn's regiment," "Cocke's regiment," and "Polk's regiment") was an infantry formation in the Confederate States Army during the Civil War, and was successively commanded by Colonels A. W. Johnson, A. T. Hawthorn, J. B. Cocke, and Lieutenant-Colonel C. Polk.  It was mustered into service on June 17, 1862, at Trenton, Arkansas, remaining active through May 26, 1865.  When Major-General Sterling Price's staff decided to designate all infantry regiments in the District of Arkansas as "Trans-Mississippi rifle regiments", the 39th Arkansas Infantry Regiment was designated as the 6th Trans-Mississippi Rifle Regiment.  One other Arkansas regiment was designated as the 39th Arkansas Infantry; that regiment being successively commanded by Colonels Hart, McNeill, and Rogan.  It was originally designated as the 39th Arkansas, but later redesignated as the 30th Arkansas Infantry Regiment.  The 39th served in the Trans-Mississippi Theater of the American Civil War and participated in all of the principal engagements in that department before disbanding on May 26, 1865.

4th Marine Infantry Regiment: The 4th Marine Infantry Regiment (French: "4 Régiment d'Infanterie de Marine, 4 RIMa" ) was a French marine regiment of the troupes de marine within the French Army.  This regiment was part of the « Quatre Grands » of the Marine Infantry along with the 1st Marine Infantry Regiment 1 RIMa, the 2nd Marine Infantry Regiment 2 RIMa, the 3rd Marine Infantry Regiment 3 RIMa, however was dissolved in 1998.  Along with the 1st Marine Artillery Regiment 1 RAMa and 2nd Marine Artillery Regiment 2 RAMa, the 4th Marine formed of the two brigades of the Blue Division.  On June 14, 2001, the GSMA of Mayotte, heir to the 4th Marine Infantry Regiment, received the color guard of the regimental colors.

Operation Primicia: Operación Primicia (] , "Operation Scoop") was a large guerrilla attack that took place on 5 October 1975, in Formosa, Argentina.  It was the largest attack ever launched by the paramilitary group Montoneros, which attempted to seize the barracks of the 29th Forest infantry regiment.  This attack worsened the Dirty War, and indirectly led to the 1976 Argentine coup d'état the following year.

Gyosaku Morozumi: Morozumi was born in Nagano prefecture.  He graduated from the 22nd class of the Imperial Japanese Army Academy in May 1905, serving initially with the IJA 58th Infantry Regiment, a new regiment which had been raised as a reserve force in the closing stages of the Russo-Japanese War.  As a second lieutenant, he returned to the Army’s Infantry Warfare School, where he specialized in armor.  His rise through the ranks was uneventful, serving a staff post with the Inspectorate General of Military Training, and a field posting as battalion commanders within the IJA 59th Infantry Regiment, IJA 1st Infantry Regiment, IJA 29th Infantry Regiment and IJA 65th Infantry Regiments and as commander of the Hongo Regimental District.  The IJA 65th Regiment was one of the units at the Battle of Nanking in 1937 during the Second Sino-Japanese War and was accused of the massacre of prisoners of war following the battle's end.

Supporting paragraphs: Operation Primicia Montoneros
Answer: Montoneros