Whilst I'm sure that I am likely to be teaching others to suck eggs, it may be helpful to know that you can access the Legion of Mary handbook, here. This evening I am celebrating Mass for the Legion, locally, with the annual Acies. The Acies is the great central annual function of the Legion. The legion handbook notes:
Bearing in mind the importance of devotion to Mary in the Legion system, each year there shall be a consecration of legionaries to Our Lady. The consecration - which shall comprise both an individual and a collective consecration - will take place on the 25 March or on a day close thereto, and will be known as the Acies.
The Latin word, meaning as it does an army ranged in battle array, is appropriate to a ceremony in which the legionaries as a body assemble to renew their fealty to Mary, Queen of the Legion, and from her to receive strength and blessing for yet another year's battle with the forces of evil.
Mass fits the bill.