Rosh Hashanah 18 - Sometimes sorrow, sometimes joy
In the times when the New Moon was determined by the Court and not by the calendar, the Court would send out messengers to far away provinces, to announce when the Holidays of Passover, Rosh Hashanah, Chanukah and Purim will be.
However, the above list omits the fast days in Tammuz and Tevet, why is that? - Because in the times of the Temple these days were observed not as fasts but as days of feasts and happiness. Still, since the prophets knew that the Second Temple will also be destroyed, they did not abrogate the fast days for good.
In fact, so many miraculous salvations happened in the days of the Second Temple that the Sages had to write down a scroll enumerating these minor festivals when fasting and eulogizing the dead was not allowed. It was called "The Scroll of Fasts." Later, with the destruction of the Second Temple, these minor festivals were also canceled. Some say that they stayed, since they were not related to the Temple. All agree that in the subsequent generations the amount of trouble and suffering magnified and people became numb to them, hence, they did not appreciate the deliverance from them either.
Art: Interior With A Family Feasting And Dancing by Willem van, the Elder Herp