Polish name is Solidarnosc (Solidarność).
Using strikes and other industrial action the union sought to block government initiatives. On Decemeber 13, 1981, the government leader Wojciech Jaruzelski started a crack-down on Solidarity, declaring martial law, suspending the union, and temporarily imprisoning most of its leaders. It took until the end of 1982 for martial law to be lifted. Throughout the mid-1980s, Solidarity persisted solely as an underground organization, supported by the Church. But by the late 1980s, Solidarity was sufficiently strong to frustrate Jaruzelski's attempts at reform, and nationwide strikes in 1988 forced the government to open a dialogue with Solidarity. In April 1989, Solidarity was legalised and allowed to participate in the upcoming elections in 1990. In these limited elections union candidates won a striking victory. By the end of August a Solidarity-led coalition government was formed and in December Walesa was elected president, resigning from his post in Solidarity. Since then the organisation has become a more traditional trade union, but a political arm was founded in 1996 as Solidarity Electoral Action. Solidarity currently has around 1.5 million members.