The first documented attempt at blood transfusion was made by Stefano Infessura of an event that occurred back in 1492. Pope Innocent VIII fell into a coma and his wise physician prescribed a blood transfusion (via the mouth as circulation wasn’t fully understood). Three 10 year old volunteer boys donated some of their blood in return for a ducat. Unfortunately for all 4, they all died.
Blood transfusion made real leaps in success rate when in 1907 Ludvig Hektoen connected the matching of blood types (first discovered in 1901) for the transfusion process.