Because he was assassinated. He was assassinated very soon after the war ended and there was no time to do everything he wanted to do. Other people took over and started implementing reconstruction ideas and eventually it turned into more exploitation and segregation and racism.
Berlin--communism was contained by splitting the city of Berlin between East and West instead of allowing the capital city to fall under the control of the USSR
Korea--the US with the United Nations partitioned Korea into North and South with the North under the influence of the USSR and the South under the influence of the West. The advance of the North was prevented and the partition remained following the Korea War.
Cuba--though Cuba became a communist nation, the US attempted overthrows and potentially an assassination of the communist leader Fidel Castro. When the USSR attempted to put missiles in Cuba, the US was able to negotiate and prevent the missiles.
The final loss of Jerusalem for European forces can be considered to be between 1270 and 1272. In the year 1270, Louis IX of France who lead the (arguably called) Eight crusade died on the shores of modern day Tunisia. This had effectively ended the Eight crusade and also led Henry III of England's son Edward to sail to Acre and try to reclaim the city. He was, however, unsucessful and had to return back to England. His demise marks the ending of the Ninth crusade which lasted from around 1271 to 1272. After this crusade no major attempt from Europe was made again to reclaim Jerusalem or any other city captured by the Crusaders in previous crusades.
