in 1846 parliament repealed the corn laws—which had imposed a tariff on imported grain—and thereby "de facto" instituted free trade. there was a widespread belief that free trade would lower prices immediately. however, this did not occur for about 25 years after repeal; the years 1853 to 1862 were famously described by lord ernle as the "golden age of english agriculture". this period of prosperity was caused by rising prices due to the discovery of gold in australia and california which encouraged industrial demand. grain prices dropped from 1848 to 1850 but went up again from 1853, with the crimean war (1853-1856) and the american civil war (1861-1865) preventing the export of cereals from russia and the united states, thereby shielding britain from the effects of free trade. britain enjoyed a series of good harvests (apart from in 1860) and the area of land under cultivation expanded, with increasing land values and increasing investments in drainage and buildings. in the opinion of historian robert ensor, the technology employed in british agriculture was superior to most farming on the continent due to more than a century of practical research and experimentation: "its breeds were the best, its cropping the most scientific, its yields the highest". ernle stated that "crops reached limits which production has never since exceeded, and probably, so far as anything certain can be predicted of the unknown, never will exceed".