Rail strikes across England, Scotland, and Wales disrupted travel for millions of passengers on Tuesday (21 June).
Around 40,000 members of the Rail, Transport and Maritime (RMT) union walked out over pay and working conditions.
Cuts meant that "RMT has no choice but to defend our members industrially", RMT general secretary Mick Lynch said.
Strikes will also take place on 23 and 25 June.
The industrial action is the biggest in the UK for more than 30 years.
A strike on the London Underground on Tuesday also furthered disruption.
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