The poem is just four short lines, but they carry a heavy, bleak picture. War arrives from the east, and it is described as "black like the bird who takes sad children." That image does a lot of work. The bird feels like a omen or a predator, something that swoops in and carries off the young. Black also suggests smoke, soot, and mourning, which fits the title's hint of factories and machinery.
In the second pair of lines, the city has been "conquered" and so has "play." Childhood itself seems to be a casualty. Then the speaker speaks plainly: "I have not lived but to fight." There is no anger in it, only a flat, tired acceptance, as if fighting is the only life the speaker has ever known. The mood is cold and grim, and the brevity makes it feel like a verdict. Nothing is explained, and that silence leaves the reader sitting with the loss.