ordered a large-scale clearance of several feet of silt. However this did not prevent an outbreak of disease in the garrison in 1841 caused by poor water supply, resulting in several deaths. To prevent the festering ditch posing further health problems, it was ordered that the moat should be drained and filled with earth. The work began in 1843 and was mostly complete two years later. The construction of the Waterloo Barracks in the inner ward began in 1845, when the Duke of Wellington laid the foundation stone. The building could accommodate 1,000 men; at the same time, separate quarters for the officers were built to the north-east of the White Tower. The building is now the headquarters of the Royal Regiment of Fusiliers. The popularity of the Chartist movement between 1828 and 1858 led to a desire to refortify the Tower of London in the event of civil unrest. It was the last major programme of fortification at the castle. Most of the surviving installations for the use of artillery and firearms date from this period. During the First World War, eleven men were tried in private and shot by firing squad at the Tower for espionage. During the Second World War, the Tower was once again used to hold prisoners of war. One such person was Rudolf Hess, Adolf Hitler's deputy, albeit just for four days in 1941. He was the last state prisoner to be held at the castle. The last person to be executed at the Tower was German spy Josef Jakobs who was shot on 15 August 1941. The executions for espionage during the wars took place in a prefabricated miniature rifle range which stood in the outer ward and was demolished in 1969. The Second World War also saw the last use of the Tower as a fortification. In the event of a German invasion, the Tower, together with the Royal Mint and nearby warehouses, was to have formed one of three "keeps" or complexes of defended buildings which formed the last-ditch defences of the capital. Restoration and tourism The Tower of London has become established as one of the most popular tourist attractions in the country. It has been a tourist attraction since at least the Elizabethan period, when it was one of the sights of London that foreign visitors wrote about. Its most popular attractions were the Royal Menagerie and displays of