This song is a satire of US government attitudes toward the Vietnam War. Country Joe McDonald released it at the height of the war after he had been discharged from the US Navy for several years. He wrote it in about 30 minutes after it popped into his head.
The song attempts to put blame for the war upon the politicians and leaders of the US military and the industry that makes its money from war, but not upon those who had to fight the war: the soldiers. It expresses the thoughts of a person trapped in the military system and forced to go to war by something called "conscription." Conscription, or the "draft" as it was called, was a system that picked young people and forced them into the military and into the war. The only other choice was jail or an attempt to "dodge the draft" for religious, physical or mental reasons. It was very hard to get out of the draft because so many people were being killed in the war that they would take just about anyone.
The song attempts to address the horror of going to war with a dark sarcastic form of humor called "GI humor." GI humor is a way people have of complaining about their situation so it will not get them in trouble and keep them from going insane in an insane environment like war.
This was the title song for Country Joe & the Fish's second album. When they performed it at Woodstock, they created one of the more memorable moments of the festival when they led the crowd in the "Fish Cheer":
"Gimme an F... Gimme a U... Gimme a C... Gimme a K..."
The album version of the Fish Cheer: "Gimme an F... Gimme an I... Gimme an S... Gimme an H..."
At Woodstock, the Fish Cheer was uncensored.
The first version of this song was an acoustic rendition recorded at Arhoolie Records Studios in El Cerrito, California, in 1965. McDonald released a limited number of copies on his own independent label, Rag Baby, many of which he distributed in October that year at a Berkeley, California, anti-war protest called the Vietnam Day Teach-In. The band started playing an electric version of the song at live shows and earned a following on the West Coast with a psychedelic sound that was coming into vogue. Signed to Vanguard Records, they released an electric version on their second album with the label, I-Feel-Like-I'm-Fixin'-To-Die, in 1967. The "Fish Cheer" came about in August 1968 at a show in New York City's Central Park when McDonald came up with it on the fly.
The tune is based on ragtime music, which is why the song is a "rag."
The Woodstock performance proved to be the legacy of Country Joe & the Fish, which was a problem. "My most famous song really couldn't get airplay," McDonald told Entertainment Weekly in 2019. "It got me banned from municipal auditoriums for a long time after. So I paid a price. But I'm proud to say that I've carried with me the reality of the Vietnam War. I'm the elephant in the room."
One person who did not appreciate this song is Billy Joel, who saw the band perform it at Woodstock when he was 20 years old. Joel told Howard Stern: "This hippie comes on stage and starts going, '1-2-3, what are we fighting for,' and I'm thinking, 'this song sucks. It wasn't even about the lyric, it sucked as a song."