Teachers will often tell you that it's a mistake to confuse the speaker of a poem with the author. But in this case, you're fine with saying, "This speaker is totally Yeats." And if he isn't, he's a dude who is the same age as Yeats and who knows all the same people and has all the same opinions about all the same experiences.
Throughout this poem, Yeats tries to grapple with how he actually feels about the unsuccessful Easter Uprising of 1916. He wrote this poem in 1921, which means he had five years to decide how he felt. But even after half a decade, he still can't come down hard on whether the uprising was a good or bad idea.
On top of that, he's not sure how he feels about the people who died or got arrested in the uprising. Sure, he's willing to mention them. But he says one of them had "ignorant good will" (18) and a "shrill" voice (20). Then there's the "drunken, vain-glorious lout" (32), which you can translate as "a cocky jerk." Still, though, he feels like he has to say something about these people and the legacy they left behind.
At the end of the day, the speaker can't get behind what happened in the Easter Uprising. But he can say that the fighters deserve to be remembered in a poem and that they'll be remembered "Whenever green is worn" (78). So in the end, he never overcomes his sense that he was right to stay out of the conflict. But he's still willing to acknowledge that the fighters didn't die for nothing.