"Vierdaagse" is Dutch for "Four day Event". The word is used for a number of annual four day sports events in the Netherlands, including ones for walking, cycling and swimming. By far the largest Vierdaagse is the walk held every July in Nijmegen, often referred to by the British as the 'Nijmegen Marches'.
This annual walk has taken place since 1909, as has been based at Nijmegen since 1925. A related Vierdaagse was also held in various locations in the Dutch East Indies between 1935 and 1939. Successful walkers received the same medal as at the Nijmegen event.
Originally a military event with a few civilians, it is now a mainly civilian event. Numbers have risen dramatically in recent years, with nearly 40,000 walkers - including about 5,000 service personnel. Since 2004 there has been an upper limit on the numbers taking part. The volume of spectators has also increased, many thousands coming to watch and encourage the flow of walkers that stretches over many miles each day.
Depending on age group and category, walkers have to walk 30, 40 or 50 kilometres on each of the four consecutive days, each day's walk following a different set route. Those who complete the march on all four days receive the 'Vierdaagse Cross'. This is an official Dutch decoration worn in uniform by members of the armed forces of both the Netherlands and many other countries. Many participants take part every year, each additional year being marked by a special medal or a number worn on the medal ribbon.
This site gives details of these medals as well as the other awards presented in connection with the event.