The poem turns a conquistador's death into a quiet, bitter joke about what conquest really is. It begins with a plain fact: when we die, our bodies lose water, and we are mostly made of it. The speaker then jumps to the idea of "discovery," which the poem calls an "old cheat." Discovering a new land, it suggests, is a kind of trick, a claim that something was found when it was really taken.
The last lines make the point sharper. Men at war "eat / nothing but places," so conquest becomes a form of hunger, swallowing whole lands instead of food. Yet the title promises defeat, and the opening image shows where that hunger ends: in a dried-out body, emptied like everyone else's.
The speaker sounds dry and unimpressed rather than angry. The mood is cool, ironic, and a little grim, with a sense that all the grand ambition comes down to something very physical and very small.