Today (July 1, 2016) marks 100 years since the start of the Battle of the Somme. It would last 141 days and become the bloodiest of World War 1.
The first day, July 1, 1916, was bloodiest day of the fighting and the bloodiest day in British military history. In total there were 60,000 British casualties on the first day alone. By the end of the battle there would be over 1 million casualties on all sides.
Short video: https://www.youtube.com/watch?v=Ab653F-fze0
Full documentary: https://www.youtube.com/watch?v=6QQnikqXglc