Step 1 : Introduction to the question "What World War I battle had the most casualties?"
...On this day in 1916, a massive joint operation between British and French forces against the Germans occurred in the Somme area in northern France. Dubbed the Battle of the Somme, it was the largest battle of the First World War on the Western Front. More than three million men fought in the battle and one million men were wounded or killed, making it one of the bloodiest battles in human history. The battle also has the distinction of being the first battle fought with tanks. The disastrous Battle of the Somme stretched on for more than four months, with the Allies advancing a total of just five miles.