The area of Rijeka was heavily fortified even before World War II (the remains of these fortifications can be seen today on the outskirts of the city). This was the fortified border between Italy and Yugoslavia which, at that time, cut across the city area and its surroundings. As Yugoslav troops approached the city in April 1945, one of the fiercest and largest battles in this area of Europe ensued. The 27,000 German and additional Italian RSI troops fought tenaciously from behind these fortifications (renamed "Ingridstellung"—Ingrid Line—by the Germans). Under the command of the German general Ludwig Kübler they inflicted thousands of casualties on the attacking Yugoslav Partisans, which were forced by their superiors to charge uphill against well-fortified positions to the north and east of the city. The Yugoslav leaders were afraid of possible English plans to disembark in Rijeka and Istria and cut them off of the Easternmost territories of the Kingdom of Italy, which were in their plans for annexation in the war's aftermath. After an extremely bloody battle and heavy losses on the attackers side, the Germans were forced to retreat. Before leaving the city, in an act of wanton destruction (the war being almost over), the German troops destroyed much of the harbour area and other important infrastructure with explosive charges. However, the German attempt to break out of the partisan encirclement north-west of the city was unsuccessful. Of the approximately 27,000 German and other troops retreating from the city, 11,000 were killed or executed after surrendering, while the remaining 16,000 were taken as prisoners. Yugoslav troops entered Rijeka on 3 May 1945. The city had suffered extensive damage in the war. The economic infrastructure was almost completely destroyed, and of the 5,400 buildings in the city at the time, 2,890 (53%) were either completely destroyed or heavily damaged.