John Gill Commentary 2 Samuel 19:3

"And the people gat them by stealth that day into the city, as people that are ashamed steal away when they flee in battle." — 2 Samuel 19:3 (ASV)

And the people got them by stealth that day into the city
Did not march into it in companies, in a public and triumphant manner, as conquerors used to do; but entered in a private manner, one by one, or a very few together, not caring to be seen or known, at least by the king, as fearing they had incurred his displeasure: but

as people being ashamed steal away when they flee in battle ;
as if they had been conquered, and not conquerors; nay, had acted a cowardly part, and ran away; and so cared not to be seen, lest they should be reproached, or suffer for their cowardice.