In 2009, Pope Benedict XVI explained in his general audience that, "The first Sunday of July was formerly marked by the devotion to the Most Precious Blood of Christ."
He thought it was a beautiful devotion, one that highlights the positive answer Jesus has to all the blood that is shed in this world, a blood that saves us and redeems us.
Here is a short prayer he prayed in thanksgiving for Jesus' sacrifice and the gift of his Precious Blood.