Marcheshvan, sometimes shortened to Cheshvan, is the second month of the civil year, and the eighth month of the ecclesiastical year on the Hebrew calendar.
The Great Flood, which according to the Bible wiped out the world, started in Marcheshvan.
Tishrei or Tishri is the first month of the civil year and the seventh month of the ecclesiastical year in the Hebrew calendar. The name of the month is Babylonian. It is a month of 30 days. Tishrei usually occurs in September–October on the Gregorian calendar.
The holiest day of the Jewish calendar, Yom Kippur, the Day of Atonement, takes place on the 10th of Tishrei.
Rosh Hashanah greeting card, 1910