mother of all

Etymology
. Popularized and given its current sense by 's claim that the impending Gulf War would be the, though had long been used in somewhat similar senses in English, and other familial terms are used with the same meaning, like granddaddy (of all traffic jams) and father (of all battles).

Phrase

 * 1)   the greatest or largest of (its kind); the most epic example of (its kind).
 * (etc)