Churchill had a fascination with the Balkans, which he saw as one of the most favorable places for operations. A recurring theme of his "Mediterranean Strategy" was his plan for the Allies to land on the Adriatic coast of Yugoslavia and advance through the Ljubljana Gap in the Alps to reach Austria in order to stake a post-war claim on Eastern Europe. The collapsing German position in the Balkans spurred Churchill's interest once again in his plans for the Ljubljana Gap, but landing in Dalmatia would require capturing north-east Italy first. On 25 August, the British 8th Army began Operation Olive, an offensive against the Gothic Line in northern Italy spearheaded by the 1st Canadian Corps with the aim of taking Pesaro and Rimini, which were to be used as ports to support the planned British offensive in Yugoslavia. The stiff German resistance on the Gothic Line, which made the best use of the natural defensive terrain of north-eastern Italy that was crisscrossed by mountains and 14 rivers, led to the 8th Army advancing far more slowly than what had been hoped and led for the plans for the Ljubjana Gate being shelved. In "Triumph and Tragedy", the last of his "History of the Second World War" books, Churchill attacked the Americans for Operation Dragoon, the invasion of southern France, to which he was opposed. As an expression of bitterness that the Americans opposed his Mediterranean strategy, Churchill claimed that if only the manpower and resources devoted to Operation Dragoon had been made available for plans to advance up the Ljubanja Gap, then the Allies would had taken Vienna in 1944 and thereby prevented the Red Army from capturing that city in 1945.