Bonta's short poem puts us in a strange, dreamlike place, and it doesn't explain itself. The speaker says they "hew to" something, meaning they cling to it or stay loyal to it, and what they cling to is "the hole of doubt." The phrase "the hanged man" gives that hole a name. It may point to the tarot card of that name, which is often linked with suspension, sacrifice and seeing things upside down, though the poem never says so outright. That's an inference, not a certainty.
In the second stanza the speaker shifts from "I" to "we." A group lands in this place of doubt, made up of people "who would walk / to see the cost." The title suggests these are marchers, people moving together for a cause. The poem implies that walking forward means facing what it will really cost.
The mood is sober and uneasy, but also stubborn. Doubt isn't treated as weakness. It's a place the speaker chooses to stay, and a place where people gather to look honestly at consequences.