In July 1939, British citizens responded for the first time to a nationwide appeal for blood donation. As academic Jenny Bangham notes in Blood Relations: Transfusion and the Making of Human Genetics (2020), “War was threatening and the Ministry of Health hoped that a nationwide transfusion service would help mitigate the bloody effects of aerial bombardment.” Responding to street posters, newspaper advertisements, and radio broadcasts, thousands of people in London, Manchester, and Bristol travelled to local hospitals to volunteer. There, their earlobes or fingertips were punctured with needles so that a few drops of blood could be collected. At recruitment centres, nurses diluted each sample in saline and passed it to a trained serologist, who determined the donor’s “blood group”—a crucial measure for ensuring compatibility between donor and recipient.Blood donation and transfusion were not new practices. Small-scale local transfusion services had already existed in several countries for nearly two decades. However, this was the first time the British government, anticipating war, directly appealed to its citizens to donate blood.As we mark World Blood Donor Day on June 14, a look at how the World Wars advanced the science of blood donation.From animal to animal, the first transfusionBlood has occupied a central place in medical thought, religious belief, and cultural imagination since antiquity. References to the transmission and significance of blood appear across numerous written traditions. Among the earliest systematic discussions is The Yellow Emperor’s Classic of Internal Medicine, a foundational Chinese medical text that contains some of the first scientific reflections on blood.Between 1450 and 1750, however, experts went beyond theoretical studies and tried transfusion. The first successful animal-to-animal transfusion was performed by Richard Lower in 1665. Two years later, in 1667, Jean-Baptiste Denys carried out the first recorded animal-to-human transfusion. The first successful human-to-human transfusion followed much later, in 1818, by James Blundell.Early experiments and success in 1825Describing Lower’s landmark experiment, author Zdravko Kvržić writes in History of Blood Donation and Transfusion Medicine (2024): “In February 1665, Lower drew blood from an exposed jugular vein of a medium-sized dog with a cannula. The dog was severely weakened, and Lower bound the larger dog along with the smaller dog and allowed its blood to flow from the cervical artery into the smaller dog. This rushing in of blood soon transfused too much, as evidenced by the returning restlessness of the engorged dog.” The experiment demonstrated, for the first time, that blood could be successfully transferred between living organisms, laying the groundwork for future research. Richard Lower (Wikipedia)More than a century later, British physician and obstetrician James Blundell advanced transfusion science by adapting the procedure for human use. Blundell transfused venous rather than arterial blood, used human donors instead of animals, and performed transfusions with a syringe. He also strongly advocated that donors and recipients should belong to the same species.Story continues below this ad James Blundell (Wikipedia)The first officially documented human-to-human blood transfusion took place on December 22, 1818. Blundell transfused approximately 12 ounces (355 ml) of blood into a male patient suffering from severe weakness and persistent vomiting. Although the patient initially improved following the procedure, he died 56 hours later. Despite this outcome, the operation demonstrated the potential of human blood transfusion. Blundell continued refining his techniques, and, according to Kvržić, “In August 1825, he performed his first successful blood transfusion of human blood.”The multiple-syringe methodDuring the 19th century, blood donation was largely informal and relied on close social relationships. Healthy volunteers—often neighbours of patients, medical assistants, or spouses—donated blood directly to those in critical condition.A significant turning point came with the discovery of human blood groups by Austrian-American biologist and physician Karl Landsteiner in 1901, which ushered in a new era of transfusion medicine. As Kvržić notes, “Although the discovery of blood groups led to an increased interest in blood transfusion, the problem with blood clotting during the procedure was still a major problem.”Beyond clotting, transfusion practice was also constrained by another limitation: the inability to accurately measure how much blood had been transferred from donor to patient.Story continues below this adAlso read | The forgotten legacy of Kadambini Ganguly, India’s first woman doctorIn response to these challenges, new techniques were developed. In 1913, Major Lawrence Bruce Lindemann introduced a multiple-syringe method designed to improve control over transfusion volume and flow. His system used a set of invaginated cylindrical cannulas, 12 20-cc syringes, and a coordinated medical team. Blood was drawn from the donor into a glass syringe (sometimes up to 50 ml), detached, and then reattached to a needle inserted into the recipient, allowing the blood to be manually injected into the patient’s vein.War and an increased demand for bloodThe outbreak of the First World War dramatically increased the demand for blood. One of the earliest documented wartime transfusions occurred in the French Army on October 16, 1914. As Kvržić describes, a physician performed a transfusion on a 25-year-old soldier who had been severely injured by heavy bombardment and had already undergone a right above-the-knee amputation. The donor was another soldier. The procedure was carried out using an unspecified direct transfusion method and, notably, without compatibility testing. By the end of 1914, the French Army had recorded 44 such transfusions. Wounded soldier being given blood plasma in Sicily, 1943 (Wikipedia)In the post-war period, the success of wartime transfusions created a sustained demand for organised blood donation systems. Hospitals sought reliable networks of donors capable of responding in emergencies. In December 1920, the Camberwell branch of the Red Cross in London received one of the earliest recorded calls for blood donors from King’s College Hospital.Under the leadership of Percy Lane Oliver, arrangements were made with voluntary donors, though questions of payment quickly arose. Oliver maintained that if compensation were introduced, it should be directed not to donors but to the Red Cross itself to support its ongoing work. Oliver’s initiative became known as the London Blood Transfusion Service. However, it functioned primarily as a coordinated donor registry rather than a modern transfusion service.Story continues below this adThe birth of blood banksThe early development of blood storage began during the First World War and expanded in the 1930s, although only a few countries—the Soviet Union, the United States, and Spain—had established systems at first. Blood supplies being drawn from an advanced blood bank, 1944 (Wikipedia)In 1917, Captain Oswald Hope Robertson, widely regarded as the first “blood banker,” showed that blood could be preserved and transported for later use. Between 1917 and 1918, he carried out 22 transfusions using stored blood. This discovery was especially relevant during the Spanish Civil War (1936–1939).Further, the Second World War advanced blood donation science—particularly in the United Kingdom. A large number of men and women turned up to donate blood. They were first asked to register their personal and medical details. The process took five minutes in total, and about 425 ml of blood was collected. The sample was then labelled and refrigerated. The United States witnessed a similar shift, where voluntary, unpaid blood donation began in selected cities and hospitals in the 1920s. British poster of 1944 encouraging people to donate blood for the war effort (Wikipedia)At the same time, medical practice was evolving as doctors began to question whether whole blood was always necessary for transfusions and turned to alternative component-based approaches. What remains undisputed, though, is that the war triggered advances in the science of blood donation.