In 1686, at Charborough Park, a meeting took place to plot the downfall of James II of England. This meeting was effectively the start of the Glorious Revolution. During the 18th century, much smuggling took place along the Dorset coast; its coves, caves and sandy beaches provided opportunities for gangs such as the Hawkhursts to stealthily bring smuggled goods ashore. Poole became Dorset's busiest port and established prosperous trade links with the fisheries of Newfoundland which supported cloth, rope and net manufacturing industries in the surrounding towns and villages. However, the industrial revolution largely bypassed Dorset which lacked coal resources and as a consequence the county remained predominantly agricultural. Farming has always been central to the economy of Dorset and the county became the birthplace of the modern trade union movement when, in 1834, six farm labourers formed a union to protest against falling wages. The labourers, who are now known as the Tolpuddle Martyrs, were subsequently arrested for administering "unlawful oaths" and sentenced to transportation but they were pardoned following massive protests by the working classes. The Dorsetshire Regiment were the first British unit to face a gas attack during the First World War (1914–1918) and they sustained particularly heavy losses at the Battle of the Somme. In total some 4,500 Dorset servicemen died in the war and of the county's towns and villages, only one, Langton Herring, known as a Thankful Village, had no residents killed. During the Second World War (1939–1945) Dorset was heavily involved in the preparations for the invasion of Normandy: beach landing exercises were carried out at Studland and Weymouth and the village of Tyneham was requisitioned for army training. Tens-of-thousands of troops departed Weymouth, Portland and Poole harbours during D-Day and gliders from RAF Tarrant Rushton dropped troops near Caen to begin Operation Tonga. Dorset experienced an increase in holiday-makers after the war. First popularised as a tourist destination by George III's frequent visits to Weymouth, the county's coastline, seaside resorts and its sparsely populated rural areas attract millions of visitors each year. With farming declining across the country, tourism has edged ahead as the primary revenue-earning sector. Dorset is largely rural with many small villages, few large towns and no cities. The only major urban area is the South East Dorset conurbation, which is situated at the south-eastern end of the county and is atypical of the county as a whole.