Truman eventually managed to break the berlin blockade by

Sending massive amounts of food and supplies by regular airlift

Explanation:.

The Berlin Blockade was a major political crisis where the Soviet Union blocked access by land to the Western occupation zone of Berlin, Germany. First started as a protest to the introduction of the West German Mark, which damaged the economy of the Soviet occupation zone in East Berlin, it lasted for almost a year, between June 14, 1948 and May 12, 1949. The Soviets hoped that the Western allies would withdraw the West German Mark when the situation inside the city became untenable. However, US president Harry Truman instead order to break the blockade by sending massive amounts of food and supplies by regular airlift to West Berlin, with flights coming and going day and night. Unable to break the Allies position, the Soviets eventually relented and lifted the blockade. The Berlin Blockade was one of the early events of the Cold War, and one that showcased how much relations between the former allies had deteriorated.