Day of the Spear

Myrmidia’s main sacred day is called the Day of the Spear, a big event in Tilea and Estalia but a minor one in the Empire. Falling on 8th Jahrdrung, it commemorates Myrmidia’s greatest victory, when she vanquished a great army of daemons. Her followers mark this day with solemn prayers and recitals from her holy books. The event culminates with displays of martial prowess by Myrmidia’s most devout followers.

Source

 * Warhammer Fantasy RPG 3rd ED -- Signs of Faith pg. 31