Prince William to attend service marking the centenary Battle of Amiens - Britain's Prince William and Prime Minister Theresa May will join 2,000 guests at a service today marking the centenary of the Battle of Amiens. Representatives of the Australian, British, Canadian, French, German and US governments will also commemorate the tens of thousands of troops killed in the four days of fighting. The Battle of Amiens sounded the start of the Hundred Days Offensive on the Western Front, which led to the Armistice in November 1918. May's visit is her second to France in under a week, coming days after she held talks with President Emmanuel Macron at his Mediterranean holiday retreat over her Brexit plan. Macron, a native of Amiens, is not himself scheduled to attend.