On 14 May 1796 Edward Jenner (age 46) inoculated eight year old James Phipps against smallpox using pus from the cowpos blisters of milkmaid Sarah Nelmes. He later injected the boy with variolous material without disease following. The boy's response indicated he was immune to smallpox. He then tested a further twenty-three people including his eleven month old son Robert. Within years the whole of Europe had been innoculated against smallpox.