After the destruction of the First Temple many years ago the Jewish people were exiled to Babylon. The conqueror Nebuchadnetzar eased some of his harsh restrictions and allowed some of the Jewish people to remain in the Land of Israel. King Nebuchadnetzar even appointed a righteous Jewish man by the name of Gedaliah Ben Achikam as the
Jewish peoples governor.
He allowed Gedaliah to administrate the entire territory. Gradually more Jews who escaped from the horrors of war to many of the other countries returned to their homes in Israel. Gedaliah knew how to govern and also knew that the Jewish people had to cooperate with the nation who conquered their land. A man named Yishmael ben Netaniah was jealous
of Gedaliah and of foreign influence and ignored the edicts of the King of Babylon and treacherously killed Gedaliah and many other Jews and Babylonians.
In the wake of Gedaliah's murder, the Jews dreaded reprisal from the King. They thought to flee to Egypt to escape. Since Egypt was a morally corrupt society the Jews didn't know if they should go. The Jewish people asked the prophet Jeremiah for his advice. Jeremiah pleaded with G-d for an answer. Finally on Yom Kippur the Jewish people were answered. Jeremiah called the Jews and told them to stay in Israel and everything would be OK.
G-d was planning to make the Babylonians act mercifully toward the Jews. But if the Jews didn't listen and go to Egypt the sword would take them. Unfortunately the people did not listen and so they packed their bags and left for Egypt. They even kidnapped Jeremiah the prophet and took him with them. Now the destruction was complete. The land of Israel was barren (empty), everyone left.
The initial event, the murder of Gedaliah, has been likened to the destruction of the Holy Temple because it cost Jewish lives and brought the end of Jewish settlements in Israel for many years. The lone survivor was Jeremiah. His prophecy came true as years later Babylon conquered Egypt and tens of thousands of Jewish lives were wiped out.
The prophets and sages declared that the anniversary of the tragedy of Gedaliah and the massacre should be a day of fasting. This day is the third of Tishrei the day after Rosh Hashanah. The fast begins before sunrise on the third of Tishrei , and ends that evening after sunset when the stars are visualized.
As you can see that on Yom Kippur G-d told the people that everything would be OK, and that they should not leave. The people did not trust in G-d. So Yom Kippur the day of atonement was promised to be a day of forgiveness to the Jewish people if only they would listen and return. If they didn't then they would have marked their own destruction as they did in the story of Gedaliah.
May the merit of the tzaddik Gedaliah ben Achikam protect us all, Amen.