The massacre at the Wujek Coal Mine in the southern city of Katowice became an iconic event in Poland’s Solidarity-era fight for freedom. Just days after the country’s last communist leader, General Wojciech Jaruzelski, imposed martial law, trade unionists at Wujek clashed with security forces.

A total of almost 3,000 miners took part in the strike to protest against military rule, which had been imposed as part of a crackdown on the burgeoning Solidarity union. The communist authorities sent more than 2,000 military and paramilitary forces to put the strike down using tanks and armored vehicles.

The stand-off turned violent and culminated with a special police unit opening fire on the demonstrators, killing nine and injuring 21.

In 2007, 15 members of the platoon responsible for the massacre were tried and sentenced to prison terms. Most received between 2.5 and three years behind bars, with the unit’s commander, Romuald Cieślak, being jailed for 11 years.

The Wujek massacre has entered modern Polish folklore as a turning point in the country’s struggle against communist rule.

At a ceremony to mark the anniversary, President Andrzej Duda lamented that the chief architects of the crime had never been held accountable.

“It is painful that those responsible for the tragedy, who gave the orders, were never held responsible and were actually never punished,” Duda said. “It is a disgrace that they were buried with honors.”

“They were traitors and bandits, but they were Poles,” Duda said, adding that this was an element of the event’s tragedy.