The National Union of Seamen was the principal trade union

Trade union

A trade union, trades union or labor union is an organization of workers that have banded together to achieve common goals such as better working conditions. The trade union, through its leadership, bargains with the employer on behalf of union members and negotiates labour contracts with...

 of merchant seafarers in the United Kingdom

United Kingdom

The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

 from the late 1880s to 1990. In 1990, the union amalgamated with the National Union of Railwaymen

National Union of Railwaymen

The National Union of Railwaymen was a trade union of railway workers in the United Kingdom. It an industrial union founded in 1913 by the merger of the Amalgamated Society of Railway Servants , the United Pointsmen and Signalmen's Society and the General Railway Workers' Union .The NUR...

 to form the National Union of Rail, Maritime and Transport Workers

National Union of Rail, Maritime and Transport Workers

The National Union of Rail, Maritime and Transport Workers is a trade union in the United Kingdom which unionises transport workers. It has more than 80,000 members, and its current general secretary is Bob Crow...

 (RMT).
The Seamen's Union was founded in Sunderland in 1887 as the National Amalgamated Sailors' and Firemen's Union. Its founder, J. Havelock Wilson became its president. It quickly spread to other ports and had become genuinely national by the end of 1888.

In 1888 and 1889 the union fought a number of successful strikes in Glasgow

Glasgow

Glasgow is the largest city in Scotland and third most populous in the United Kingdom. The city is situated on the River Clyde in the country's west central lowlands...

, Seaham

Seaham

Seaham, formerly Seaham Harbour, is a small town in County Durham, situated south of Sunderland and east of Durham. It has a small parish church, St Mary the Virgin, with a late 7th century Anglo Saxon nave resembling the church at Escomb in many respects. St Mary the Virgin is regarded as one of...

, Liverpool

Liverpool

Liverpool is a city and metropolitan borough of Merseyside, England, along the eastern side of the Mersey Estuary. It was founded as a borough in 1207 and was granted city status in 1880...

 and other major ports.