The tragic saga of the imprisonment of Rabbi Meir ben Baruch ("Maharam") of Rothenburg came to a close when his body was ransomed, 14 years after his death, by Alexander ben Shlomo (Susskind) Wimpen.
"Maharam" (1215?-1293) was the leading Torah authority in Germany, and authored thousands of Halachic responsa as well as the Tosaphot commentary of the Talmudic tractate Yoma. In 1283 he was imprisoned in the Ensisheim fortress and held for a huge ransom, but he forbade the Jewish community to pay it (based on the Talmudic ruling that exorbitant sums should not be paid to free captives, as this would encourage the taking of hostages for ransom). For many years Maharam's disciple, R. Shimon ben Tzadok, was allowed to visit him in his cell and recorded his teachings in a work called Tashbetz.
Even after the Maharam's passing in 1293, his body was not released for burial until it was ransomed by R. Alexander, who was subsequently laid to rest at his side.
Links: A brief biography
Adar 4 is the yahrtzeit (anniversary of the passing) of Rabbi Leib Sarah's (1730-1791), a disciple of Rabbi Israel Baal Shem Tov. One of the "hidden tzaddikim," Rabbi Leib spent his life wandering from place to place to raise money for the ransoming of imprisoned Jews and the support of other hidden tzaddikim.
Link: More on R. Leib Sarah's
In 1555, Pope Paul IV segregated the Jews of Rome in a walled quarter surrounded by gates that were locked at night. The ghettoed Jews were then subjected to various forms of degradation as well as restrictions on their personal freedoms.
During the French Revolution, Italy was conquered by Napoleon Bonaparte. On the 4th of Adar (Tuesday, February 20, 1798) the Ghetto was legally abolished. It was reinstated, however, as soon as the Papacy regained control.