Beat-a-retreat

the forced or strategic withdrawal of an army or an armed force before an enemy, or the withdrawing of a naval force from action.
the act of withdrawing, as into safety or privacy; retirement; seclusion.
a place of refuge, seclusion, or privacy:
The library was his retreat.
an asylum, as for the insane.
a retirement or a period of retirement for religious exercises and meditation.
Military.

a flag-lowering ceremony held at sunset on a military post.
the bugle call or drumbeat played at this ceremony.

the recession of a surface, as a wall or panel, from another surface beside it.
to withdraw, retire, or draw back, especially for shelter or seclusion.
to make a retreat:
The army retreated.
to slope backward; recede:
a retreating chin.
to draw or lead back.
beat a retreat, to withdraw or retreat, especially hurriedly or in disgrace.
verb (mainly intransitive)
(military) to withdraw or retire in the face of or from action with an enemy, either due to defeat or in order to adopt a more favourable position
to retire or withdraw, as to seclusion or shelter
(of a person’s features) to slope back; recede
(transitive) (chess) to move (a piece) back
noun
the act of retreating or withdrawing
(military)

a withdrawal or retirement in the face of the enemy
a bugle call signifying withdrawal or retirement, esp (formerly) to within a defended fortification

retirement or seclusion
a place, such as a sanatorium or monastery, to which one may retire for refuge, quiet, etc
a period of seclusion, esp for religious contemplation
an institution, esp a private one, for the care and treatment of people who are mentally ill, infirm, elderly, etc
n.

c.1300, “a step backward;” late 14c., “act of retiring or withdrawing; military signal for retiring from action or exercise,” from Old French retret, noun use of past participle of retrere “draw back,” from Latin retrahere “draw back, withdraw, call back,” from re- “back” (see re-) + trahere “to draw” (see tract (n.1)). Meaning “place of seclusion” is from early 15c.; sense of “establishment for mentally ill persons” is from 1797. Meaning “period of retirement for religious self-examination” is from 1756.
v.

early 15c., “to draw in, draw back, leave the extremities,” from retreat (n.) and in part from Old French retret, past participle of retrere. Meaning “to fall back from battle” is mid-15c. Related: Retreated; retreating.
see: beat a retreat