As usual with Sen, McCarthy, there is a mixture of truths, half-truths, and lies. As an example of the latter, Sen. McCarthy claimed that it was Gen. Marshall who prevented the US Army from reaching Prague before US troops. In fact, the decision was ultimately made by Gen. Eisenhower, reflecting the collective desire of the JCS to end the conflict with Germany as soon as possible in preparation for a projected invasion of Japan. It is only with hindsight that we now know that the resources that could have been used to counter the Soviets in Eastern and Central Europe did not have to be transferred to the Pacific against Japan.
For a thoughtful account of the trade off between military objectives and political goals involved in Eisenhower’s decision, and the potential costs in terms of the lives of American troops, read the Epilogue to this report:
https://books.google.com/books?id=Trda4LmkhdsC&printsec=frontcover#v=onepage&q&f=false