During the First Italian War for Independence in 1849, Pope Pius IX went into exile to Gaeta. He went there with Don Giovanni Merlini, third superior general of the Fathers of the Most Precious Blood.
While the war was still raging, Merlini suggested to Pope Pius IX that he create a universal feast to the Precious Blood to beg God's heavenly aid to end the war and bring peace to Rome. Pius IX subsequently made a statement on June 30, 1849 that he intended to create a feast in honor of the Precious Blood. The war soon ended and he returned to Rome shortly thereafter.
On August 10 he made it official and proclaimed that the 1st Sunday in July will be dedicated to the Precious Blood of Jesus Christ. Later, Pope Pius X assigned July 1 as the fixed date of this celebration.
After Vatican II the feast was removed from the universal calendar, but a votive Mass in honor of the Precious Blood was established and can be celebrated in the month of July (as well as most other months of the year). Some dioceses, especially in Europe, still celebrate the July 1 feast day.
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