In Belgium, at the site of a major World War I battle (Vimy), some 83 year old artillery shells containing mustard gas were discovered to be leaking. Several thousand local civilians were evacuated from the area until the chemical shells could be disposed of. This sort of thing happens every year along the World War I trench lines that crossed Europe from the English Channel to the Swiss border. Elsewhere in Europe, unexploded bombs and shells are still found in populated areas. But few of the World War II munitions are chemical, as few chemical were used during that war.