5 About a hundred years previously, Britain, after many vicissitudes, had been brought back to the Christian religion by Our predecessor of immortal memory, Gregory the Great, when he sent thither a band of Benedictine monks under the leadership of St. Augustine. It is surely wonderful, then, that in this short interval it should have been distinguished by so firm a faith and so ardent a charity that, like a river overflowing and irrigating the surrounding land, it should want to send many of its best sons to other nations to gain them to Christ and to bind them closely to His Vicar on earth. This seemed to be its manner of thanking God for having received the benefits of the Catholic religion, civilization, and Christian culture.
Source: Ecclesiae Fastos (Vatican.va)