Case by case, answers are mixed:
1. For A-H empire, no. It ceased to exist. For the Czech, Slovene, Slovak, Ruthenian, Bosnian, Croat, Austrian, Polish and Hungarian soldiers who fought, answer is mixed. Hungarians lost big--half their country. Czechs, Slovaks and Yugoslavs got their independence, so they'd answer differently. The Italians redeemed some of their terre irredente (unredeemed lands), but got Mussolini's fascism on the rebound, winning the war but losing the peace.
2. For Serbs, yes. Their state continued to exist. For A-H empire, no.
3. For France, yes. A-H empire, no.
4. For the Finns, yes. They exist as a people with their own state. They view the alternative--being press-ganged back into Russia's Soviet empire--as unthinkable slavery. The Russians now view Finnish independence as irreversible and the Finns as unconquerable, exactly where the Ukrainians wish to end up.
5. American Civil War: If a confederate sniper at Jubal Early's raid on Fort Stevens in July 1864 had assassinated Lincoln and McClellan become president-elect in November 1864, McClellan would have negotiated an armistice, allowing for two countries where there is now one. The Confedracy annexes Cuba as a slave state. Imagine WWI with two Americas, one free, the other slave or recently ex-slave. Germany wins and the treaty of Brest-Litovsk remains in place. When you don't like the result we got, imagine the counterfactuals.
The lieutenant who yelled "get down you damn fool!" at Lincoln after the army doctor standing next to Lincoln was shot and killed was Oliver Wendell Holmes. His service on the Supreme Court was the second most valuable service to his country.
6. Vietnam: the Vietnamese think so. But not the French and the Americans.
7. Israel vs Egypt and Syria: without the 1967-70 war of attrition, there would have been no Yom Kippur War in 1973. No YKW and Sadat doesn't go to Jerusalem in 1977 and Camp David in 1979 to negotiate the peace that convinces the Arabs that Israel's existence is permanent and irreversible by war.
8. Iraq vs Iran, 1980-88. A shame both sides could not lose. Arab Baathist Stalinism vs Persian theocratic fascism.
9. The Balkan Wars, 1912-13: The Greek islands and all of northern Greece with Greek populations are Greek and not Turkish. Bulgaria, Macedonia and Montenegro are independent. For the small states ejecting their colonial overlords, it's worth it. For the ir imperial occupiers, no.
Most these examples illustrate Tim Snyder's principle: "to get better a country must lose its last colonial war."
The US was smarter than most empires: it left the Philippines voluntarily in 1946 and Haiti and Nicaragua in 1933-35. The Russians and the Japanese have never left any subjugated territory voluntarily, accomplishing the rare feat of making the French, the Germans, the Italians, the Brits and the Dutch look smart.
