assailen

Middle English

From Old French assaillir, assalir, from Late Latin assalīre; equivalent to assaile +‎ -en (infinitival suffix).

assailen

To assail or assault; to loot or attack.
- c. 1390, John Wycliffe, transl., edited by Josiah Forshall and Frederic Madden, The Holy Bible, Containing the Old and New Testaments, with the Apocryphal Books, in the Earliest English Versions (Wycliffe's Bible), volume II, Oxford UP, published 1850, I. Paralipomenon VII.21, page 334, column 2:
  Forsothe men of Geth borun in the lond killiden hem, for thei ȝeden doun to assaile her possessiouns.
  Forsooth, men of Gath born in the land killed him, for they went down to assail her possessions.
To begin or launch an assault or military operation.
To bother, hurt, or injure (used often of malign forces)
To affect; to induce towards (used of feelings)
To lure or draw into sin, perfidy, or iniquity.
To insult; to launch into a tirade or rant against.
To try or undertake (an endeavour or behaviour)
(rare) To become (dead or slumbering)
(rare) To have intercourse; to mate (used of animals).
(rare) To assay; to investigate something.
(rare) To plead; to beseech.

¹ Sometimes used as a formal 2nd-person singular.

“assail(l)en, v.”, in MED Online, Ann Arbor, Mich.: University of Michigan, 2007, retrieved 2018-08-17.
“sailen, v.(1).”, in MED Online, Ann Arbor, Mich.: University of Michigan, 2007, retrieved 2018-08-17.