Why does beah provide so much detail in the setting and plot before describing the war?

Which line in this excerpt from "the love song of j. alfred prufrock" by t. s. eliot uses synecdoche? shall i say, i have gone at dusk through narrow streets and watched the smoke that rises from the pipes of lonely men in shirt-sleeves, leaning out of windows? i should have been a pair of ragged claws scuttling across the floors of silent seas.