The Collaborative International Dictionary of English v.0.48:
Prolonge \Pro*longe"\, n. [F. See Prolong.] (Field Artillery) A rope with a hook and a toggle, sometimes used to drag a gun carriage or to lash it to the limber, and for various other purposes. [1913 Webster]WordNet (r) 3.0 (2006):
prolonge n 1: a rope fitted with a hook and used for towing a gun carriage