late 14c., earlier asaut (c. 1200), "physical attack (on a person), sudden violent onslaught (on a place)," from Old French asaut, assaut "an attack, an assault, attacking forces" (12c.), from Vulgar Latin *adsaltus "attack, assault," from ad "to" (see ad-) + Latin saltus "a leap," from salire "to leap, spring" (see salient (adj.)). The -l- was restored, as in fault (n.), vault (n.1). In law by 1580s; historically, assault includes menacing words or actions coupled with present means to effect them; battery is an actual blow.
"attack physically," early 15c., assauten, from Old French asauter, assauter, from Vulgar Latin *assaltare (see assault (n.)). Related: Assaulted; assaulting.