Origins of the Feast of Saint Joseph
While the veneration of St. Joseph on March 19 existed in various calendars as early as the 10th century and was added to the Roman calendar by Pope Sixtus IV in 1480, it was the intervention of leaders like Ferdinand II that helped ensure it became a major, mandatory celebration.
Following the victory at the Battle of the White Mountain in 1620 AD (a key early battle in the Thirty Years' War), Emperor Ferdinand II (a staunch Catholic and Habsburg) promoted devotion to Saint Joseph.
In 1621, Pope Gregory XV (reigned 1621–1623) subsequently issued a decree setting March 19 as an obligatory feast day for the universal Church.