Since I doubt most people here heard of him, brief summary - general Wojciech Jaruzelski was II World War era political prisoner, then soldier of eastern Polish Army full time from its founding under colonel Berling to capture of Berlin. After war, he was promoted to officer and joined the Party, getting higher posts until he became minister of defence.
In 1980, he became prime minister then led de-facto bloodless coup against communist hard-liners and started to distance country from the USSR. To this end, he decided to stave off incoming Soviet intervention, much like 1953 and 1968 ones, by pre-emptively arresting opposition leaders, dispersing army from bases then declaring curfew to quell dissent, saying he has country fully under his control so intervention isn't needed anymore (and making disarming army by surrounding bases, like Czech one was, impossible, thus presenting unspoken threat to Soviet leadership had they decided to attack anyway)*.
In 1989, Jaruzelski began on his own initiative talks with democratic opposition about transforming the country from mono-party to plural democracy. Then, one year into his five year term as first president of democratic Poland, resigned saying communist party's loss in election cannot allow him to continue in good conscience knowing public opinion is opposed to continuation of his party's rule and policies.
Ironically, the reason he might have resigned was that Tadeusz Mazowiecki, very decent man, new prime minister and leader of democratic opposition was favourite to winning the presidency in his stead. What we got instead was illiterate peasant Wałęsa becoming the president though, Mazowiecki resigning too to not be worse, and 3 years of such inept right wing rule the post-communist parties overwhelmingly won 1993 elections, despite massive loss 4 years earlier. But by then Jaruzelski decided to retire from public life anyway.
Who knows, maybe it have been better if Jaruzelski and Mazowiecki stayed, as both had excellent ministers and since then country wouldn't have been damaged to such degree. But then again, maybe we needed a lesson that elections matter and their resignations basically put an end to any arguments country isn't a democracy now.
*For that he is, by the way, despised by current polish right-wingers who say he denied the nation "glorious revolution" that would have toppled Soviet Union. In 1980. And not be crushed like, oh, last 10 "glorious revolutions" in our history were
Then again, by now almost anyone seems competent compared to them.