<P> The last decades of the 19th century saw concerted political campaigns for Irish home rule . Ireland had been united with Britain into the United Kingdom of Great Britain and Ireland with the Act of Union 1800 after the Irish Rebellion of 1798, and had suffered a severe famine between 1845 and 1852 . Home rule was supported by the British Prime minister, William Gladstone, who hoped that Ireland might follow in Canada's footsteps as a Dominion within the empire, but his 1886 Home Rule bill was defeated in Parliament . Although the bill, if passed, would have granted Ireland less autonomy within the UK than the Canadian provinces had within their own federation, many MPs feared that a partially independent Ireland might pose a security threat to Great Britain or mark the beginning of the break - up of the empire . A second Home Rule bill was also defeated for similar reasons . A third bill was passed by Parliament in 1914, but not implemented because of the outbreak of the First World War leading to the 1916 Easter Rising . </P> <P> By the turn of the 20th century, fears had begun to grow in Britain that it would no longer be able to defend the metropole and the entirety of the empire while at the same time maintaining the policy of "splendid isolation". Germany was rapidly rising as a military and industrial power and was now seen as the most likely opponent in any future war . Recognising that it was overstretched in the Pacific and threatened at home by the Imperial German Navy, Britain formed an alliance with Japan in 1902 and with its old enemies France and Russia in 1904 and 1907, respectively . </P> <P> Britain's fears of war with Germany were realised in 1914 with the outbreak of the First World War . Britain quickly invaded and occupied most of Germany's overseas colonies in Africa . In the Pacific, Australia and New Zealand occupied German New Guinea and Samoa respectively . Plans for a post-war division of the Ottoman Empire, which had joined the war on Germany's side, were secretly drawn up by Britain and France under the 1916 Sykes--Picot Agreement . This agreement was not divulged to the Sharif of Mecca, who the British had been encouraging to launch an Arab revolt against their Ottoman rulers, giving the impression that Britain was supporting the creation of an independent Arab state . </P> <P> The British declaration of war on Germany and its allies also committed the colonies and Dominions, which provided invaluable military, financial and material support . Over 2.5 million men served in the armies of the Dominions, as well as many thousands of volunteers from the Crown colonies . The contributions of Australian and New Zealand troops during the 1915 Gallipoli Campaign against the Ottoman Empire had a great impact on the national consciousness at home, and marked a watershed in the transition of Australia and New Zealand from colonies to nations in their own right . The countries continue to commemorate this occasion on Anzac Day . Canadians viewed the Battle of Vimy Ridge in a similar light . The important contribution of the Dominions to the war effort was recognised in 1917 by the British Prime Minister David Lloyd George when he invited each of the Dominion Prime Ministers to join an Imperial War Cabinet to co-ordinate imperial policy . </P>

How did england become the most dominant power in the world in the 1800s