The eleventh hour of the eleventh day of the eleventh month marks the signing of the Armistice, on 11th November 1918, to signal the end of World War One.
At 11 am on 11 November 1918 the guns of the Western Front fell silent after more than four years continuous warfare.
Remembrance Sunday is held on the second Sunday in November, which is usually the Sunday nearest to 11 November. Special services are held at war memorials and churches all over Britain.
Source: http://www.woodlands-junior.kent.