How would they have connected the dots?

I just posted about Eisenhower's Farewell Address to the Nation, January 17, 1961 by Dwight D. Eisenhower. I mentioned this line.

We now stand ten years past the midpoint of a century that has witnessed four major wars among great nations.

What were the four major wars among great nations Eisenhower references between 1900-1960? World War I and II obviously. Almost certainly the Korean War is the third. But what about the fourth? Eisenhower adds the rider that "Three of these involved our own country." The challenge is that the fourth does not involve the US. That probably rules out the Russian Civil War (1918-21) which involved a number of the European powers but also 13,00 American troops in Archangelsk and Vladivostok.

The Spanish Civil War (1936-39) might be a candidate as that famously served as a precursor proxy for the major European powers pre-WWII. While America was officially committed to non-intervention, some 2,800 private citizens volunteered and served in the Lincoln Brigade. So possibly a candidate.

The Russo-Japanese War (1904-05)? Certainly that involved great powers, but only the two of them. As the Russo-Japanese War has never had much currency in the US outside military historians, I rather doubt that was what Eisenhower was alluding to in his speech.

Maybe its the Suez Crisis (1956-57) which involved Egypt on one side and France, Britain, and Israel on the other, with the US, the USSR and the UN, working in the background to defuse the situation.

Possibly he is alluding to the Cold War. It certainly meets the criteria of involving multiple great nations. But it is a metaphorical war and fits poorly in the class of other wars among great powers (WWI, WWII, Korea) which Eisnehower references. A possibility but seemingly an unlikely one.

There are multiple other candidates. The Chinese Civil War (1945-50), the Vietnam Civil War (1955-64), maybe the Indian Partition (1947-48). However, all these, while often involving various great nations, were all fundamentally internal, civil wars, i.e. not directly conflicts between great nations.

So what was the major war between great nations between 1900 and 1960 which did not involve the US but which an informed audience in 1961 would instantly recognize? I guess I will have to go with the Russo-Japanese war as best meeting the criteria but I am pretty confident that is not what Eisenhower had in mind. An interesting mystery and a great example of how hard it is to recapture the zeitgeist or mindset of a time past.