Dwight Eisenhower will rank as one of the most important American Presidents and individuals because of three decisions he made, the least known of which was probably actually the most important one.
The first decision of course that Ike made was to launch D-Day om June 6, 1944.
It was a strategic decision of the highest order, because any delay could well have meant a failure of the Allied deception campaign that the invasion was going to cross the Pas De Calais, rather than be launched at Normandy.
Although Hitler was in very deep trouble by June 1944, with restless generals who some might wonder had mixed motives in the West, hence the July 20 coup once the breakout from the Normandy beaches was secured, had things been delayed long enough either by decision or by defeat, it is possible that the V-2 weapons might have started to do some real damage to British morale, as it was already something of an issue by June, and at full production, the Germans could have leveled London every bit as much as with nuclear weapons.
Since our whole ability to conduct expeditions on the European continent hinged on the British "aircraft carrier," time wasn't really on Ike's side.
As to the decision Ike is most famous for on June 5, to go ahead and attack on June 6, the night before, he had decided not to go, as the weather was too poor; this was to be round two.
The next night, the meteorologists said there should be a break in the weather, and so although not all the staff at the final meeting concurred, Ike concluded that he should go, in no small measure because the deception campaign was at risk.
He then went into his study, and wrote the following memo:
"Our landings in the Cherbourg-Havre area have failed to gain a satisfactory foothold and I have withdrawn the troops. My decision to attack at this time and place was based upon the best information available. The troops, the air and the Navy did all that Bravery and devotion to duty could do. If any blame or fault attaches to the attempt it is mine alone."
And then he went to sleep, and Bravery and Devotion did the rest.
That was Ike's second most important decision, almost a tie with his decision to enforce Brown v Board of Education.
Ike didn't really like that decision, truth be told, as he thought that it lacked a sense of the reaction it would trigger in the South and even in Kansas where he had served at Leavenworth.
Nonetheless, Ike believed in the Republic, including the role of the Court, and when Arkansas Governor Faubus challenged the decision, there was zero hesitation on Ike's part to enforce Federal Law with the National Guard if need be, and which of course proved to be necessary.
As to Ike's most important decision, it's less well-known, because of what he decieded not to do.
What Ike decided not to do was not preemptively strike Russia while we still could without risking a nuclear disaster.
In an exercise known as "the Solarium Exercise," Ike was presented with the facts of the accelerating Russian nuclear weapons, bombers, and missiles programs that by the end of the decade at the latest would clearly be able to strike the United States with large numbers of nuclear weapons.
Prior to that exercise in 1953, after 1945, Assured Destruction wasn't mutual, as only the United States could strike the Soviet Union with nuclear weapons. Russian bombers couldn't have survived both the flight and our air defenses, and there were no ICBM's back then.
It was a clean kill shot on the Soviet Union, unless you lived in Western Europe or Japan, and yet Ike dismissed such ideas, saying at one point, in effect, "Your warplan calls for 3,400 nuclear weapons at 7,400 megatons of yield to be laid down from East Germany to Vietnam and Korea, all Eastern Europe, Russia, and China included. 500 million dead or wounded is the forecast. You are mad, as only a Genghis Khan adventurer would do such a thing."
That's a pretty big decision to have made, as because of that decision, we still live with a nuclear armed Russian Federation that can as Putin pointed out last year,"Burn down your civilization in 30 minutes."
Although it would really take a couple of days to do that, and only if we just sat there and didn't launch massive counter-force strikes on Russian nuclear facilities and C4RSI targets, plus bombardments of selected politico-industrial targets to signal resolve to take them with us unless war ceased on reasonable terms, it's still a risk to our survival, and yet I think Ike was right.
To launch a preemptive strike to efface whole countries from the Earth with no warning, which is what was being proposed in effect, would alter our form of government, even as when you read enough Soviet history, you aren't naive that that government was anything but a very real threat to our survival.
This is just as if you read contemporary Russian politics, you won't be naive that it is anything but rather serious business when dealing with the Russians to this day, if we're also still here, both of us, something the Russians really ought to be more thankful for, and more trusting therefore with us too.
Maybe that will be Ike's legacy someday too, that Russia trusts someone in the international system, which would be the most important Presidential legacy of all.