Read the text. The figure of speech is shown in bold.

The lawn in front of Chief Mulligan’s house was always the best tended on the street and the two small mulberry trees on each side of the stoop were always well trimmed. They were two soldiers, chests thrust out sternly, on guard day and night for the chief of police.

From Eleanor Estes, The Moffats. Copyright 1941 by Eleanor Estes