boots on the ground n.pl. personnel deployed under military command. Editorial Note: Boot dates to before World War II as indicating a military recruit or a green enlisted man. (source: Double-Tongued Dictionary)
Further reading
Ryan, a wildland firefighter from Asheville, North Carolina, asked about bagger, a derogatory term for “a lazy or amateur firefighter.” The term likely comes from military slang, where bagger is short for dirtbagger or S-bagger, most likely deriving...
The Very Hungry Caterpillar (Bookshop|Amazon) had an earlier title: A Week with Willie the Worm. This is part of a complete episode. Transcript of “The Very Hungry Caterpillar’s First Title” Here’s another book title that...