The Italian or Mediterranean campaign began with the Allied invasion of Sicily began 10 July 1943  at the Gulf of Gela.  Both amphibious and airborne forces were involved.  The US contributed the 7th Army (Lt-Gen Patton) and the British contributed the 8th Army (Gen Montgomery).  The 8th Army included the 1st Canadian Infantry Division and the 1st Canadian Tank Brigade.  On  17 August 1943, the Germans were able to evacuate most of their forces to mainland Italy.

On 3 September 1943 (Operation Baytown), the 8th Army landed in Italy.  On the same day, the Italian government agreed to an armistice with the Allies. Five days later, the armistice was announced to the Italian public by radio.  The German forces would continue to defend Italy on their own.  

Two more amphibious landings took place on 9 September 1943: Operation Avalanche (US 5th Army, Salerno) and Operation Slapstick (British 1st Airborne Division, Taranto).  As the allied forces moved north, they encountered the Apennine Mountains.  These mountains cover half the width of Italy around Abruzzo.  Some of the peaks reach almost 1000 m and the rough terrain and the flood prone rivers make it easy to defend.  

In early October 1943,  Army Group Commander in Southern Italy, Field Marshal Albert Kesselring ordered the preparation of a series of defensive lines south of Rome. Two of these lines (Volturno, Barbara) were used for delay actions while the Winter line (Gustav, Bernhardt, Hitler/Senger) was finished.  The Winter line practically halted the 5th Army advance along the west coast by the end of 1943.   The harsh winter conditions stalled the 8th Army in the east near Ortona.  

It took four major offensives between January and May 1944 before the line was eventually broken by a combined assault of the Fifth and Eighth Armies (including British, American, French, Polish, and Canadian corps). The American forces took possession of Rome on 4 June 1944

After the Allied invasion of Normandy, the U.S. VI Corps and the French Expeditionary Corps (CEF) were moved to the European theatre for the invasion of Southern France. They were replaced by  the Brazilian 1st Infantry Division, the U.S. 92nd Infantry Division ( both in the second half of 1944), and the U.S. 10th Mountain Division (January 1945).

In summer 1944, the Allies advanced beyond Rome, taking Florence and closing up on the Gothic Line.  The Gothic Line was attacked and penetrated during Operation Olive (25 August 1944) without a decisive victory. In early 1945,  the British 5th Infantry Division and I Canadian Corps  moved to northwestern Europe.

By March 1945,  U.S. IV Corps (1st Brazilian Division and the newly arrived U.S. 10th Mountain Division) were able to finally push the German defenders from the commanding high point of Monte Castello and the adjacent Monte Belvedere and Castelnuovo, depriving them of artillery positions that had been commanding the approaches to Bologna.  The Allies’ final offensive commenced with massive aerial and artillery bombardments on 9 April 1945.

By 25 April 1945, the  rapid advance towards Turin by the Brazilian division  took the German–Italian Army of Liguria by surprise, causing its collapse.

 General Heinrich von Vietinghoff officially surrendered on 29 April 1945.

Authors note:  Although the official nomenclature for the period is the 11th Army Tank Regiment (The Ontario Regiment (Tank)), 12th Army Tank Regiment (Three Rivers Regiment (Tank)), and 14th Army Tank Regiment (The Calgary Regiment (Tank)) – This site will refer to the units as current Ontario Regiment (OntR), Three Rivers Regiment (TRR), and the Calgary Regiment (CalR)