15 April: Regiment is designated by the US War Department for re-activation with the 85th Infantry Division, one of the first all-draftee divisions.
15 May: Activation of the regiment with the division at Camp Shelby, Mississippi. Colonel Donald A. Stroh assumes command of the 339th Infantry. Presentation of colors and first arrival of draftees.
July: Colonel Stroh is reassigned and regimental command is given to Colonel Paul J. Vevia.
October-November: Battalion and regimental size field maneuvers begin in Camp Shelby training areas and designated sites outside of the camp boundary.
23 March: The 85th Infantry Division begins participation in corps maneuvers in DeSoto National Forest in Louisiana.
June: Division is relocated to the Desert Training Center at Camp Pilot Knob, California.
August: Relocation to Camp Coxcomb, California.
October: The 85th Infantry Division relocates to Fort Dix, New Jersey, for staging prior to overseas assignment.
26 October: Colonel Paul Vevia is relieved of command of the 339th Infantry for medical purposes and stateside assignment. Colonel James T. Matthews assumes command.
December: Relocation to Camp Patrick Henry at the Hampton Roads Port of Embarkation.
24 December: 339th Infantry and Division Headquarters set sail from Norfolk, Virginia aboard the USS GENERAL ALEXANDER E. ANDERSON. The 310th Engineer Battalion sails aboard the USS GENERAL WILLIAM A. MANN and the 910th Field Artillery Battalion sails aboard HMS ANDES.
2 January: USS GENERAL ALEXANDER E. ANDERSON arrives at Casablanca. Regiment bivouacs at Camp Don B. Passage until January 4, 1944.
7 February: Reassignment for 85th Division to the "Invasion Training Center" at Port Aux Poules, Algeria. Six weeks of amphibious landings and beach assault training follow at Arzew and Oran.
10 March: The 339th Infantry is ordered to Oran and the allied Port of Embarkation. The regiment boards HMS LETITIA and sets sail for Naples, Italy after nightfall.
14 March: HMS LETITIA docks at Port of Naples near midnight. Arrival is marked by German air raid on the city. The 339th Infantry moves by truck and foot to a bivouac at Casanova, three miles from the front lines near Minturno, Italy, where it is attached to the 88th Infantry Division.
15 March: Headquarters staff and battalion officers visit the front line positions held by the 88th Infantry Division to effect relief of the 349th Infantry Regiment.
17-18 March: First night on the line for the 339th Infantry. 3rd Battalion, 339th Infantry relieves part of 349th Infantry, 88th Infantry Division near Castleforte and San Lorenzo, Italy at midnight. Remainder of 339th Infantry Regiment effects relief following night and sector passes to CO of 339th Infantry on 19 March. First battle casualties occur in E Company within a few hours of the unit's arrival.
23 March: Colonel Matthews is hospitalized with fever from an organ infection.
26 March: 339th Infantry relieved from front line, returns to Casanova staging area. The hospitalized Colonel Matthews is relieved of duty for health reasons and evacuated. Lt. Colonel Brookner Brady assumes command of the 339th Infantry.
28 March: 339th Infantry relieves the 350th Infantry, 88th Infantry Division in front lines above Minturno, Italy.
11 April: Three POW's taken by a patrol from Company I, 339th Infantry. These are the first prisoners captured by the 85th Division in combat.
1 May: The 339th Infantry regiment is assigned the combat area northwest of Minturno, centered around the village of Tremensuoli and the seaside villa of Scauri, held at that time by the 338th Infantry, 85th Infantry Division. The unit is facing the outer defenses of the "Gustav Line" held in this sector by the German 94th Infantry Division.
3 May: 339th Infantry relieves the 338th Infantry in line from Minturno to Scauri, and assumes responsibility for guarding Garigliano River Bridge on Highway 7.
11 May: "The Big Push". Operation DIADEM begins at 2300 hours. The 339th Infantry attacks promptly at H-Hour, with the 1st Battalion containing Scauri and enemy held Domenico Ridge east of the town. The 2nd Battalion advances into the area between Tremensuoli and Scauri, objectives of Hills 58, 79, and Intermediate Ridge. The 3rd Battalion crosses Capo di Acqua and assaults Hills 69 and 66. Casualties are heavy within first few hours.
13 May: Battle along front line continues. 1st Battalion, 337th Infantry relieves 3rd Battalion, 339th Infantry at Hill 69 after nightfall and continues attack on Hill 66, which is repulsed. Remnant of F Company surrounded on Intermediate Ridge finally capitulates at dusk. G Company holds Hill 79 against continued counterattacks with no relief.
15 May: First signs of German withdrawal. 1st Battalion moves onto Domenico Ridge. Hill 79 is secured by G Company, 2nd Battalion. 3rd Battalion reorganized and moved back to front line near Tremensuoli.
16 May: Mount Scauri is taken. 339th Infantry Regiment receives replacements and sets out on Highway 7 toward Fondi and Formia.
18 May: 339th Infantry takes Mount Cefalo and Mount Merano.
19 May: After intense fighting, the town of Itri is captured by the 2nd Battalion, 339th Infantry and elements of the 88th Infantry Division.
22-23 May: Mount Calvo, Mount Della Rocca, and Sonnino are taken at minimal cost. Sonnino is a smashing success with the wholesale capture of the enemy garrison and breaking of the highly vaunted "Hitler Line".
1 June: Castel d'Ariano, Mount Fiore, Mount Salamone, and Mount San Sebastiano are taken by companies of the 339th Infantry, flanking last German elements on the western plains several miles south of Rome.
5 June: Liberation of Rome and passage through the city. Fighting continues north of Rome as the regiment advances to the Olgiata Heights where it is ordered to halt.
7 June: The 85th Infantry Division is ordered back to rest and refit. The 339th Infantry is ordered to a bivouac established in the "King's Forest" at Lido di Roma. For three weeks, the regiment rests, refits, and undertakes training.
15 August: The 85th Infantry Division is ordered to relieve American units along the Arno River. The 3,000 yard front stretches from the enemy-held town of Montespertoli to Signa west of Florence. The 339th Infantry is assigned a sector from the riverside village of Limite to Signa.
15 August: Montespertoli is captured. Allied elements cross the Arno River.
20 August: additional sector on western flank assigned to 339th Infantry and then to 310th Engineer Battalion.
24-26 August: 339th Infantry is relieved and withdraws from the Arno River line.
10 September: 85th Infantry marches through Florence and northward toward the Apennines Mountains in preparation for assault on the German held "Gothic Line".
13 September: Attack on the Gothic Line at Mount Verruca located east pf Il Giogo Pass and hill masses south of the height. H-hour at 6:00 AM, the 1st and 2nd Battalions, 339th Infantry step off and come under heavy fire.
14 September: Battle for Hill 732 begins. F Company makes several assaults with no success. I Company ordered to the action at Hill 732 to make further attempts on the fortified hill. B Company is over extended in their attack. In a surprise counterattack, the company is badly mangled and two platoons nearly wiped out.
17 September: Mount Verruca is captured and Il Giogo Pass secured by the 338th Infantry, 85th Infantry Division and the 91st Infantry Division. Preparations are made to immediately advance northward toward Mount Coloreta.
21 September: Mount Coloreta is captured by 339th Infantry.
2 October: Capture of villages of La Martina, Osteria, and Colle de Tattini. Heavy fighting ensues with I Company near the latter village. An early morning attack through fog captures the enemy garrison and drives out the other defenders, despite the uneven numbers engaged- enemy defenders outnumber the attackers by two to one.
4 October: Quinzano is captured. 339th Infantry advances on San Martino, preparatory to attack on enemy-held Mount Bibele.
17 October: 339th Infantry seizes the heights of Anta Ana, Gagliano, and captured mountain side town of Castlevechio.
28 October: Colonel Brookner Brady is relieved of command of the 339th Infantry for reassignment. Colonel William Fitts, Jr., from 85th Infantry Division Headquarters assumes command. Lt. Col. Richard Smith, 3rd Battalion CO, is relieved of command for health reasons and reassigned. Major Floyd Minor assumes command of the battalion. Lt. Col. Charles Mudgett, 2nd Battalion CO, is relieved of command for chronic health reasons and reassigned. Lt. Colonel John Hesse, S-3 at Regimental HQ, 339th Infantry assumes command of the battalion.
10 November: The regiment is relieved from the front and sent to Montecatini Terme for rest and refit.
2 December: 339th Infantry moves to bivouac near town of Gagliano for refitting and training.
23 December: The 339th Infantry is ordered to move to the Serchio Valley to support the 92nd Infantry Division which is under attack.
1 January: Colonel Fitts returns to division staff and Lt. Colonel John English assumes command of the 339th Infantry.
6 January: 339th Infantry returns to Gagliano bivouac from Serchio Valley area.
January-February: Winter Line operations near Mount Grande.
March: Training near Gagliano, including river crossing training. In late March, the 85th Infantry Division is assigned to IV Corps preparatory to move back into North Apennines front lines near Mt. Grande, south of Bologna.
April: Breakout of the North Apennines and onto the Po Valley plain. 85th Infantry Division ordered to follow up in corps attack and drives to the Po River.
20 April: 339th Infantry attached to 1st Armored Division for drive into the Po Valley.
25 April: 339th Infantry crosses the Po River one day after the 337th and 338th had crossed.
26 April: 1st Battalion, 339th Infantry enters Verona and crosses the Adige River. Motorized task forces of the 2nd and 3rd Battalions, 339th Infantry move northward into Cazzo and Castlebelforte.
2 May: Unconditional surrender of German armies in Italy. G Company, 339th Infantry motorized patrol goes to Brunico where they discover political prisoners being held in a mountain resort. Amongst the prisoners is Albert Blum, former chancellor of Austria. Meanwhile, "Task Force Minor" (3rd Battalion, 339th Infantry) discovers priceless Italian art and sculpture removed from homes, churches and museums throughout Italy by German forces, boxed and marked for shipment to Berlin, many of them addressed directly to Herman Goering.
4 May: Patrol of C Company from "Task Force Webster" (1st Battalion, 339th Infantry), sets up a roadblock in the Brenner Pass and makes contact with a motorized patrol of the 103rd Infantry Division, Seventh Army operating in Austria. The Italian border is closed by Combat Team 9.
7 May: Regimental headquarters established at Dobbiaco begins to process German prisoners, war material, and searches for enemy stores.5 June: 339th Infantry in bivouac near Mel, Italy, where it holds the last awards ceremony prior to transfers from unit.
16 August: The 339th Infantry and 85th Infantry Division boards the USS WEST POINT in Naples and leaves Italy for the United States.
25 August: USS WEST POINT arrives at Hampton Roads, Virginia where the GI's are welcomed home with a steak dinner. The returning soldiers are assigned to Camp Patrick Henry.
25 August: The 339th Infantry is formally deactivated.
26 August: The 85th Infantry Division is deactivated.