From the LCMS website:
Early in the third century A.D., Laurence, most likely born in Spain, made his way to Rome. There he was appointed chief of the seven deacons and was given the responsibility to manage church property and finances. The emperor at the time, who thought that the church had valuable things worth confiscating, ordered Laurence to produce the “treasures of the church.” Laurence brought before the emperor the poor whose lives had been touched by Christian charity. He was then jailed and eventually executed in the year 258 by being roasted on a gridiron. His martyrdom left a deep impression on the young church. Almost immediately, the date of His death, August 10, became a permanent fixture on the early commemorative calendar of the Church.