Which of the Truman Doctrine, Churchill's Iron Curtain Speech and the Berlin Blockade marked the beginning of the Cold War?
Just a bit confused on which one of those started the Cold War. Some thoughts would help a lot!
There is, of course, no objective way to answer this as there was no official beginning of the Cold War. You can make a case for any of these. My argument would be that the Truman Doctrine was the most important marker of the beginning of the Cold War.
Churchill's speech, of course, came before the Truman Doctrine. However, it was not a statement of official policy. It was just an exhortation on the part of a person who was at that point a private citizen, albeit a very famous one.
Until someone took official notice of Churchill's warning and acted upon it, you cannot really say the Cold War had begun. The announcing of Truman Doctrine did this. Once Truman had enunciated his doctrine, it was quite clear that conflict with the communists was to be an official policy of the United States.
If you have to pick one of these as the beginning of the Cold War, I would go with the Truman Doctrine since it is the first concrete action by a government among your choices.