Roger Irving Lee (1881-1964) played significant scientific and leadership roles in overcoming the clinical impediments to blood transfusion in the 1910s. He developed the first successful anticoagulant system, paraffinized glass, and the first sterile system for indirect transfusion without defibrination, the Lee-Vincent flask. He used citrate as an anticoagulant before those generally credited with its discovery did. He introduced surgical antisepsis of the donor site and a practical system for maintaining typed blood for a large hospital donor and transfusion service. He was Oswald Robertson's mentor at Harvard as well as his commanding officer in the Harvard Medical Unit on the Western Front during World War I. Lee sent Robertson to perform "his preserved blood cells transfusion" in the casualty clearing stations of the British Third Army and provided Robertson's group with O donors, enabling the most important medical development of the war. Lee put the pieces of modern blood banking and transfusion together.