were "won" - the US, for example, came into WWI as the struggle was literally in its last gasps.
http://en.wikipedia.org/wiki/World_War_IAs for WWII, once the Japanese bombing of Pearl Harbor in December 1941 had furnished FDR with a reason to enter the conflict, it is true that US military intervention, especially in the notable battles of the South Pacific in 1942 and 1943, helped turn the tide for the war in the Pacific. Insofar as the European part of that war was concerned, however, the Europeans did a lot to help themselves.
There were resistance movements in each Axis or Axis-occupied country, including Germany itself, that were more or less successful depending on individual circumstances. In BushCo terminology, of course, members of such groups would be labelled as "insurgents" or even "terrorists." In addition to these, British failure to succumb to the German air war, Russians fighting desperately in their own territory, including battles such as Stalingrad, and the Allied, primarily British-led, campaigns in North Africa in 1942 did a lot to decimate German military strength even before the Allied invasions of Sicily in 1943 and Normandy in 1944 where American troops were represented among Allied Forces in large numbers.
http://en.wikipedia.org/wiki/World_War_IIIt's not quite fair to characterize either the Korean or Vietnam Wars as "Republican" Wars. At best, the record is mixed. US troops had actually occupied South Korea from 1945-1949; Russian troops had occupied the North until 1948. US authorities had not taken the threat of invasion seriously despite power struggles between the North, supported by the communist governments of Russia and China, and the South supported by us. The North invaded the South in June 1950 when Truman was President and the US response was to use US troops still stationed in nearby Japan. The armistice was actually concluded under Eisenhower in 1953-1954.
http://en.wikipedia.org/wiki/Korean_WarAlthough the Vietnam War is offically credited with beginning in 1955 (while Ike was Prez), US "advisors" had been in the area since 1950, supporting the French, as Vietnam was part of the French colonial empire. Eisenhower continued this particular support but would not actively commit US troops to the area, unless the British would also commit to participating - which they would not do. The French left in 1954 after the battle of Dien Bien Phu and advised the US to get out too. We should have listened. The subsequent Geneva Conference granted independence to Vietnam, Laos and Cambodia. Unfortunately, the North and the South were not reconciled; the US ended up as puppetmaster for yet another anti-democratic tyrant - something we seem to keep repeating. JFK's role was apparently minimal, although he was President when the anti-democratic tyrant (Diem) was assassinated in November 1963; JFK himself was assassinated a couple weeks later. After that, LBJ expanded the scope of the war and it became what those of us who came of age during that period remember. Tricky Dick inherited that war in 1969. The Paris Peace Accords were signed in 1973 during Nixon's term, but it wasn't until after all US troops had left after the fall of Saigon in 1975 under President Gerald Ford that we were considered to have "lost" that war. So Vietnam was both a Democratic and a Republican war - with lots of blame to go around - and lots of light still to be shed on the various shenanigans involved.
http://en.wikipedia.org/wiki/Vietnam_War#Exit_of_the_Americans:_1973.E2.80.931975I do believe that it is fair to say that Afghanistan and Iraq are "Republican" Wars because they were both begun with deliberate intent by an Republican Administration in order to secure oil and/or oil pipeline resources for Big Oil. There are absolutely none of the nuances of Korea or Vietnam, even though oil may have been a partial factor in Vietnam. This is in spite of all propaganda to the contrary about Al Qaeda, or making the world safe from terror, or Saddam's WMD (non-existent as it turned out) or even 9-11 - which provided them with a lot of cover for what they intended to do anyway. That they received Democratic support for these wars is beside the point. As we all know now - and many of us knew then - the intelligence was wholly concocted to make people believe things that were not true. That some Dems were stupid enough to believe it should make us look for more intelligent candidates to replace them. Obama inherited these wars and, IMO, he had darn well better put an end to them - sooner rather than later. But so far, they are not "his" ... not quite yet, at least.