The first of three projected battlecruisers for the Polish Navy, Solidarnoç's construction was continually delayed and interrupted by shipyard strikes in Gdansk. Her main armament was to be domestically-made triple 12" guns but the armament industry was so far behind schedule that Poland elected to adapt American 12" guns destined for a cancelled Alaska-class large cruiser. Solidarnoç, carrying the largest guns in the Baltic, was completed just two months before Germany invaded Poland.

While working up, it was discovered that 'B' turret had serious problems that only complete removal could alleviate. While Solidarnoç was in drydock having the turret removed, Germany moved East and the war was on. Polish spies had foretold the arrival of heavy German naval units, so the drydock was flooded and Solidarnoç, minus her 'B' turret, went forth to battle. Caught by Scharnhorst, Schleswig-Holstein, and Lützow off Gdansk in the opening moments of the war, Solidarnoç was sunk in a shower of 11" shells, but not before two hits from her domed 12" turrets eventually forced Scharnhorst into port for repairs.