St. Dominic pray for us! We do not have many surviving letters from the founder of the Dominicans, but we know that this Spanish saint was well-traveled throughout southern Europe. His mission was preaching and teaching in order to bring back souls who had strayed into heretical groups, particularly the Albigensians.
And, of course, he prayed the Rosary to great effect.
In 1216, St. Dominic met St. Francis of Assisi in Rome. The Lord had shown St. Francis to St. Dominic in a dream he had the night before they met. They struck up a friendship.
In honor of that meeting and the subsequent friendship, on the feast days of their respective founders, Franciscans and Dominicans are known for getting together as their founders did so many years ago.