Sentence:  Unsinkable slowed and stopped , hundreds of brilliant white flares <WSD>swayed</WSD> eerily down from the black , the air raid sirens ashore rose in a keening shriek , the anti-aircraft guns coughed and chattered - and above it all motors roared and the bombs came whispering and wailing and crashing down among the ships at anchor at Bari . 
Meaning of the word marked with <WSD> tags:  move or walk in a swinging or swaying manner