Thus, the putting-in-place of the final piece of Roosevelt's and Truman's grand design for a free world--a piece that they had tried and failed to put in place in their day--would be an accomplishment to be proud of.
They would feel pride after seeing the final element of their plans taking shape.
mnli hypothesis: They would feel pride after seeing the final element of their plans taking shape. premise: Thus, the putting-in-place of the final piece of Roosevelt's and Truman's grand design for a free world--a piece that they had tried and failed to put in place in their day--would be an accomplishment to be proud of.