The Yugoslavs achieved a breakthrough after a series of hard-fought encounters along the Syrmian Front in late 1944 and early 1945. Present at the pivotal Battle of Knin, the Yugoslav 4th Army then spent most of spring and early summer advancing north through Dalmatia with the intent of taking Trieste without help from Western Allies, thereby justifying a claim to the de jure Italian port. The 4th Army was led by Petar Drapšin, who had previously led the incorporated 8th Corps until he was promoted to the rank of lieutenant general.
Italian Front
On the Italian front, Western Allied forces advanced towards Trieste after breaching the Gothic Line in early March 1945. Under Lieutenant General Sir Bernard Freyberg, the New Zealand 2nd Division, having captured Faenza on 14 December 1944, reorganized on the south banks of the Senio River on 8 April 1945. There it paused to prepare for what would be the final Allied offensive in Italy. After a brief respite, the division raced on, crossing the Santerno, Gaiana, Idice, and the Po rivers. They took Padua on 28 April, crossing the Isonzo on 1 May and reaching Trieste the next day. The division had covered a distance of in less than a week.
Battle
By 30 April, the Partisans had surrounded the port city entirely. They began moving on 1 May in with the help of fighters that had infiltrated the city before the arrival of the main force. By 30 April elements of the Yugoslav force had taken multiple strategic locations from Globočnik's force such as the university, courthouse, and military hospital. On the morning of 1 May, parts of the eastern force broke through at Ricmanje and Botač and entered the city. According to Yugoslav reports, resistance had been overcome save a few isolated pockets of Germans, focused around Opčine and the harbor. By the evening of 1 May, Partisans had taken the Elba battery factory and Sabo park, where they were joined by about 50 armed Triestino antifascists. There the 4th Brigade of the 9th Dalmatian Division met and attacked a force of about a thousand German and Chetnik soldiers. On the morning of 2 May this culminated in a two hour firefight followed by the surrender of the enemy force.:281–283,429 By the end of 2 May, with the arrival of the New Zealand force, most of the 13,000 Chetnik irregulars assisting the German defenders surrendered. Fighting lasted into the next day. The remaining German pockets on the north side of the city, the largest of which being the Opčine pocket, surrendered by the end of 3 May.:282–283
Aftermath
The city was jointly occupied by the New Zealanders and Partisans until June 1945, when it came under rule of a UN-mandated military provisional government as a provision of the Treaty of Peace with Italy. It would remain a de-facto free state until it was partitioned between its two neighbors in October 1954. This was later reaffirmed in the Treaty of Osimo, where it was split de jure between Italy and Yugoslavia.
