🔗=============>> The WWII Germany > The MTO > Cassino/Anzio to Rome Submodule <<=============​🔗
​​prior MTO section:  Naples to Cassino/Anzio                                                   next MTO section:  Northern Italy
Cassino/Anzio to Rome pages:   Breakthrough & Breakout     Drive on Rome     Italy OrBat, May '44    
     –––––––––––––––––––––––––––––––– MTO - Breakthrough and  Breakout ––––––––––––––––––––––––––--––––––––
Victory at Monte Cassino
Victory at Monte Cassino
bigpigeon.us webpage WWII Germany  > The MTO > Cassino/Anzio to Rome > Breakthrough & Breakout, © 2025 by Robert A. Christiansen, updated by RAC 26 Oct 2025
​
In  mid-May 1944 in the Mediterranean Theater, the German defenses in the western end of of the Gustav Line collapsed, US forces broke out of the Anzio Beachhead and the Allies were able to resume their drive northward into central Italy.​

Work in Progress
Cassino to Rome Overview
In mid-May 1944, a concerted Allied offensive called Operation Diadem finally broke through both the Gustav Line in southern Italy.
  • As part of Operation Diadem, Polish Forces finally captured the Monte Cassino Abbey in the Fourth Battle of Monte Cassino.
  • Allied forces advanced in a generally northwest direction from the Gustav line. 
  • Allied Anzio Beachhead units broke out and also advanced generally northwest.
  • ​The German Army abandoned Rome, which was occupied by US troops on 4 June 1944.

Before reaching Rome, Allied forces had to push aside two German armies and pass through two secondary German defensive lines, the Hitler Line and the Caesar C Line, both shown on the accompanying map.
Order of Battle Overview, 10 May 1945
Italian Front Order of Battle Overview - 10 May 1944
Official Scalable "Jumpoff" Map
Timeline:
  • 5 March: 15th Army Group commander General Alexander initiates plan to to attack with Allied forces concentrated on west end of front.
  • 11 May: Operation Diadem begins.
  • 23 May: Anzio breakout begins.
  • 25 May: VI Corps from Anzio and II Corps from the Gustav Line meet near the coast southeast of  Littoria, now Latina, 15 miles east of Anzio.
  • 25 May: VI Corps 
  • 29 May: 3rd Infantry Division, on VI Corps right, transferred to II Corps.
  • 30 May: 36th Infantry Division penetrates gap in Caesar C Line.
  • 2 Jun: Valmontone on highway 6 falls to II Corps 3rd Infantry Division.
  • 4 Jun: First US troops enter Rome.
The Operation Diadem Map
The accompanying  map shows the Gustav Line breakthrough during Operation Diadem, from May 11 to May 23. Note that in the Fifth Army sector, US and French forces have already penetrated the Hitler Line.

Operation Diadem is also called the 4th Battle of Monte Cassino, since the key part of the operation was the struggle between Polish and German troops on Monte Cassino.
Advance Past the Gustav Line
Advance Past the Gustav Line
The Anzio Beachhead Breakout
The accompanying map shows progress during the first three days of the VI Corps breakout from the Anzio Beachhead. Units from left to right are the 45th Infantry Division, 1st Armored Division, 3rd Infantry Division, and the US/Canadian 1st Special Services Force.

Note Velletri near the top of the map. North of Velletri is the Velletri Gap, which will provide a route northward to Highway 6 between the Alban Hills to the west and the Lepini Mountains to the east. 
Breakout from Anzio - the First Three Days
Breakout from Anzio - the First Three Days

Pottawattamie Area WWII Dead - WWII Germany > The MTO > Cassino/Anzio to Rome > Breakthrough & Breakout   ​​02-02 - WWII Germany > The MTO > Cassino/Anzio to Rome > Breakthrough & Breakout: (two dead, updated 27 Oct 2025)
  • II Corps came from the Gustav Line as part of Operation Diadem, VI Corps from the Anzio Beachhead.
  • Operation Diadem deaths after 25 May 1944 are in Cassino/Anzio to Rome > Drive on Rome.
† Madden, Jerry Agnew, SN O-1312691, US Army, Pott. Co.
  • Co. F, 350th Inf. Regt., 88th Inf. Div., II Corps, Fifth Army; DOW 12 May 1944, near Minturno, SW of Cassino, Lazio, Italy.
  • WWII Germany > The MTO > Cassino/Anzio to Rome > Breakthrough & Breakout
​† Wood, Fred Joseph, SN 37-428-828, US Army, Harrison Co. & Valley Co., ID
  • First Special Services Force, VI Corps, Fifth Army; KIA 23 May 1944 near Cisterna, Anzio Beachhead, Lazio, Italy.
  • WWII Germany > The MTO > Cassino/Anzio to Rome > Breakthrough & Breakout @ Capture of Cisterna
                                       

     ██  Sources for Big Pigeon's WWII Germany > The MTO > Cassino to Rome webpage  ██
  • The webpage header photo, Victory at Monte Cassino, shows Polish soldier Emil Czech announcing the end of the Fourth Battle of Monte Cassino at the ruined abbey on 18 May 1944.

(Needs editing and distribution to subpages as it was copied from the old Naples to Rome webpage) Wikipedia's campaign webpages: US Army Center for Military History campaign brochures for WWII campaigns in Italy:​​​ ​US Army Center for Military History histories of WWII in Italy: Italian campaign maps:​ Other maps: Other sources:
  • https://www.reddit.com/r/europe/comments/1agzlz7/benedictine_abbey_in_monte_cassino_italy/#lightbox​

​(Needs editing and distribution to subpages as it was copied from the old Cassino 4 to Rome webpage)
  • Cassino to the Alps (scalable maps) (United States Army in World War II, Mediterranean Theater of Operations series, Ernest F. Fisher Jr., 1989, CMH #6-4) - http://www.ibiblio.org/hyperwar/USA/USA-MTO-Cassino/index.html.
  • The webpage header image Rome 5 Jun '44 is courtesy of the World War II Museum in New Orleans, LA. It shows General Mark Clark, who commanded the US 5th Army in Italy, in Rome just after liberation.
  • The Order of Battle Overview, 10 May 1944 map is courtesy of the New Zealand website, http://tothosewhoserved.org/nz/army/nzarmy08/chapter01.html. On this date, New Zealand forces were part of the British X/10th Corps northeast of Cassino.
  • The Operation Diadem - Advance Past the Gustav Line and Liberation of Rome maps by Gene Thorp are taken from Rick Atkinson's The Day of Battle.
  • The Breakout from Anzio - the First Three Days map is courtesy of battlearchives.com.