Trine immersion was the universal rule of the Catholic Church.  cf. Greg. Nyss. The Great Catechism, p. 502 of this edition.  So Tertull. de Cor. Mil. c iii., Aquam adituri, ibidem, sed et aliquanto prius in ecclesia, sub antistitis manu contestamur, nos renuntiare diabolo et pompæ et angelis ejus.  Dehinc ter mergitamur.  Sozomen (vi. 26) says that Eunomius was alleged to be the first to maintain that baptism ought to be performed in one immersion and to corrupt in this manner the tradition of the apostles, and Theodoret (Hæret. fab. iv. 3) describes Eunomius as abandoning the trine immersion, and also the invocation of the Trinity as baptizing into the death of Christ.  Jeremy Taylor (Ductor dubitantium, iii. 4, Sect. 13) says, “In England we have a custom of sprinkling, and that but once.…As to the number, though the Church of England hath made no law, and therefore the custom of doing it once is the more indifferent and at liberty, yet if the trine immersion be agreeable to the analogy of the mystery, and the other be not, the custom ought not to prevail, and is not to be complied with, if the case be evident or declared.”