Turn tail

A box-lobby lion or a Regent-street animal . . . will never bite, and, if you offer to attack him manfully, will fairly turn tail and sneak off.

[H]e stormed at me all through the lessons in a very violent manner of scolding, [...] I was often tempted to turn tail, but held my ground for all that, and got some profit of my lessons; [...]

Morning found us still vainly toiling through the passage. At last, in despair, we turned tail, ran out to sea, and sailed clear round Bassakanna to our objective, Malu.

Five of the enemy planes were shot down and the remainder turned tail.

The men blew up two oil pipelines in eastern Libya near the rebel-held Sarir fields, before turning tail and speeding back west.