body. March 24, 1848 – Start of the First Schleswig War ( or Three Years' War ()). The First Schleswig War was the first round of military conflict in southern Denmark and northern Germany rooted in the Schleswig-Holstein Question, contesting the issue of who should control the Duchies of Schleswig and Holstein. The war, which lasted from 1848 to 1851, also involved troops from Prussia and Sweden. Ultimately, the war resulted in a Danish victory. A second conflict, the Second Schleswig War, erupted in 1864. June 5, 1849 – Denmark becomes a constitutional monarchy. United Kingdom September 16, 1840 – Joseph Strutt hands over the deeds and papers concerning the Derby Arboretum, which is to become England's first public park. August 10, 1842 – The Mines Act 1842 becomes law, prohibiting underground work for all women and boys under 10 years old in England. March 25, 1843 – Marc Isambard Brunel's Thames Tunnel, the first tunnel under the River Thames and the world's first bored underwater tunnel, is opened in London. May 4, 1843 – Natal is proclaimed a British colony. April – The Fleet Prison for debtors in London is closed. July, 1848 – Public Health Act establishes Boards of Health across England and Wales, the nation's first public health law, giving cities broad authority to build modern sanitary systems. Royalty Queen Victoria was on the throne 20 June 1837 until her death 22 January, 1901. The wedding of Queen Victoria and Prince Albert of Saxe-Coburg and Gotha took place in 1840. Ireland The Great Famine of the 1840s caused the deaths of one million Irish people and over a million more emigrated to escape it. It is sometimes referred to, mostly outside Ireland, as the "Irish Potato Famine" because one-third of the population was then solely reliant on this cheap crop for a number of historical reasons. The proximate cause of famine was a potato disease commonly known as potato blight. A census taken in 1841 revealed a population of slightly over 8 million. A census immediately after the famine in 1851 counted 6,552,385, a drop of almost 1.5 million in 10 years. The period of the potato blight in Ireland from 1845 to 1851 was full of political confrontation. A more radical Young Ireland group seceded from the Repeal movement and attempted an armed rebellion in the Young Irelander Rebellion of 1848, which was unsuccessful. Western Europe