Everybody knows how severely Europe suffered from epidemics of small-pox in the last part of the eighteenth and first part of the nineteenth centuries, and how the ravages of that disease were first checked by Jenner’s wonderful discovery. Nevertheless, small-pox did not entirely disappear from Central Europe until the year 1870. The reason for this is found in the fact that compulsory vaccination was introduced in only a few states, and even in them was not properly enforced, and also in the fact that people did not until later begin to realize that vaccination insures immunity only for a period of 12–15 years at most. Consequently new recruits, if they had already been vaccinated once, were not revaccinated when they began to serve. But since sporadic outbreaks of small-pox continued to occur in the Prussian army, orders were issued in the year 1834 that all recruits must be vaccinated. The result was that from that time on, the Prussian troops were very rarely attacked by the disease. The same measure was adopted in Württemberg in 1833, in Baden in 1840, in Bavaria in 1843, in Brunswick in 1858, in the Kingdom of Saxony in 1868, and in the Grand Duchy of Hesse in 1869. Compulsory vaccination did not exist in Prussia or Saxony before the Imperial Vaccination Law was passed in the year 1874; the result was that large numbers of children were never vaccinated. The anti-vaccinationists, especially in the ‘sixties, carried on a vigorous agitation, and this had the effect of increasing the number of unvaccinated persons; the number of revaccinated persons had always been small. In South Germany compulsory vaccination for one-year-old children was introduced in the first part of the nineteenth century—in Bavaria and Hesse in 1807, in Baden in 1815, in Württemberg in 1818—but revaccination was not enforced until 1874, when the Imperial Vaccination Law was passed. The small-pox mortality in Prussia prior to the year 1870 is indicated by the following table, which shows the number of deaths per 10,000 inhabitants: 1831–40 2·6 1841–50 1·7 1851–60 2·1 1861–5 3·5 1866–7 5·2 1867–8 1·8 1868–9 1·9 1869–70 1·7 In the year 1864 an epidemic of small-pox had broken out, and the war of 1866 had helped it to spread; but in the year 1868 the disease began to abate, so that by the middle of the year 1870 almost all of Prussia was free from small-pox, as will be set forth in greater detail later on. In South Germany the small-pox mortality was even lower; in Bavaria it was 0·85 in the years 1861–70, in Württemberg it was 0·9 in the same years, and in the Grand Duchy of Hesse it was 1·9 in the years 1866–70.[250] 1. _The Small-pox Mortality in France in the Years 1870–1_