Alright, I have removed a couple of comments for the same reason, they were not informative, comprehensive, or in-depth. Do not just name a song. Explain the history of that song. For example, since both mentioned this song, explain who wrote the "Ballad of the Green Berets;" when was it written and what was the context of the writing; what was the general public's reaction--was it a major hit?
"The Ballad Of Two Brothers" by ex-rockabilly Autrey Inman made the country top 20 in 1968, and the pop top 50. Although it supports US presence in Vietnam, it is really more of a slam against anti-war protestors.
This is a common theme of the period's prowar media. Unlike the anti-Japanese and anti-German propaganda of WWII, and the anti-communism of the cold war, the prowar crowd of the '60s seemed more obsessed with domestic opposition than foreign enemies.
Yes there were various ones that were well liked at the time. Now something to remember is that despite the narrative often given of the flower power generation a large number of people were conservative and the war was well supported by a great number of people.
As for the best examples of pro war songs most of them were not so much pro war as they were anti protester. For example Merle Haggard fighting side of me and Okie from Muskogee were both in the billboard top 100.
Now the most famous is of course as mentioned earlier The Ballad of the Green Berets and that song was on of the most popular of that year selling around 9 million copies. To put that in some perspective it outsold both The Beatles and The Rolling Stones highest singles of that year. Two other songs managed to Chart near the top of the billboard charts that had a strong pro war message and funnily enough they were both spoken word. these two were An open letter to my teenage son and Gallant men both reached the top 20.
Theses were all popular songs that charted well in their respective genre charts. Now even at the time there was a ghetto so to speak between country and pop music in terms of chart success. So to put it in a slightly simplified way pro war songs were mostly country songs and thus had a hard time hitting the top 100 but nonetheless were very popular amongst the country listeners.