This Paul Newman movie doesn't get very good reviews .. perhaps because of its subject matter. Even with his passing there has been very little mention of his portrayal of General Groves. Nevertheless, General Groves presided over one of the most monumental projects of human endeavor and I believe Mr Newman played that role well.
He was fine but was a bit dashing for a somewhat portly and pompous Groves. That Groves was not quite so dashing and yet so effective would have been an interesting irony to explore.
While it's true that Newman looks nothing like Groves himself, he still was extremely well in the role. I like how in his later years got to stretch his acting talent and play guys like this.
"I know you're in there, Fagerstrom!"-Conan O'Brien
The movie "Hiroshima" had Richard Mazur as Groves, and he did a fine job, even looking like him to a great extent. This movie deals mostly with the ethical implications of whether or not to use the bomb, while also showing the Japanese leadership and their mindset regarding surrender. It shows that had the bomb not been used, it would have taken a huge invasion and many years to defeat the Japanese, who were prepared to fight a national guerilla war to achieve a settlement much more favorable to them than the unconditional surrender the Allies were demanding. Who knows how many would have died if we hadn't dropped the bomb and had to invade Japan and fight that war.
Paul Newman overacted in many of his roles, especially early in his career. He got better as he got older, though he still had that tendency now and then.