c. 1200, savacioun, saluatiun, sauvacioun, etc., originally in the Christian sense, "the saving of the soul, deliverance from the power of sin and admission to eternal bliss," from Old French salvaciun and directly from Late Latin salvationem (nominative salvatio, a Church Latin translation of Greek soteria), noun of action from past-participle stem of salvare "to save" (see save (v.)).
The general (non-religious) sense of "protection or preservation from destruction, danger, calamity, etc." is attested by late 14c. Also from late 14c. as "source, cause, or means of salvation; a preserver, defender." Salvation Army, with quasi-military organization and a mission to spark revival among the masses, is attested from 1878; it was founded 1865 as the Christian Mission by Methodist evangelist the Rev. William Booth (1829-1912).