Xerxes, the father of Artaxerxes, was murdered by political aids in August, 465 BC. Scribes recorded Xerxes' assassination date on a clay tablet known as a Babylonian Astronomical Text.(1)(2) Scholars have translated the text to show Xerxes' murder occurred sometime between August 4 to 18, 465 BC.(3) Upon his father's death, Artaxerxes became king of Persia.

Scholars use the Babylonian Astronomical Text to determine that Artaxerxes' reign began in August, 465 BC.(4)(5) Furthermore, scientifically dated Elephantine papyri corroborate that Artaxerxes became king in August, 465 BC. To show such support, let's discuss how a king's reign was counted in the 5th century BC.
 

The Hebrews, Babylonians, and Egyptians used a common principle for counting the years of a king's reign in the 5th century BC. The year that a new king came to power was called the year of the king's ascension, which ended the day before New Year's Day.

Each of the three cultures observed New Year's Day at a different time of the year. After Artaxerxes became king in August 465 BC, the Hebrew culture would have observed New Year's Day on October 17, 465 BC.(6)(7) By the Hebrew calendar, King Artaxerxes' ascension year lasted two months from August, 465 BC to October 16, 465 BC.

After the Jewish New Year, the Egyptian New Year occurred on December 17, 465 BC. By the Egyptian calendar, King Artaxerxes' ascension year lasted four months from August, 465 BC to December 16, 465 BC.

Finally, after the Egyptian New Year, the Babylonian New Year occurred on April 14, 464 BC. By the Babylonian calendar, King Artaxerxes' ascension year lasted eight months from August, 465 BC to April 13, 464 BC.

Scholars conclude that an ascension year for a Persian king always lasted less than one year. I have charted the length of King Artaxerxes' ascension year and listed New Year's Day for each of the three cultures below:

So New Year's Day was pivotal to how each culture numbered King Artaxerxes' years as ruler of Persia.

How the Years of King Artaxerxes' Reign Were Counted

Each of the three cultures counted King Artaxerxes' first year beginning with New Year's Day. For instance, the Hebrew culture started counting King Artaxerxes' first year on October 17, 465 BC. The Egyptians did not begin counting King Artaxerxes' first year until December 17, 465 BC. So each culture kept track of King Artaxerxes' years based on his ascension to power in August, 465 BC, then numbered the years on each subsequent New Year's Day. The following graph shows when each culture began counting King Artaxerxes' first official year.

Since each culture maintained a distinct calendar, there were three ways to count King Artaxerxes' years. According to the chart above, on November 1, 465 BC, the Hebrews would have been in Artaxerxes' first year. But, the Egyptians and Babylonians were still in Artaxerxes' ascension year. On December 20, 465 BC, the Hebrew and Egyptian counting would have been in Artaxerxes' first year, while the Babylonians were still in the ascension year.
 

Is it possible to prove that King Artaxerxes ascended to power in August, 465 BC with the Egyptian papyri?

Consider the following papyrus wherein the Hebrew date of Kislev 21 matches the Egyptian date of Mesore 1, in the 6th year of King Artaxerxes.

Kislev 21 = Mesore 1, Year 6 of Artaxerxes(8)

Kislev is the 9th Hebrew month. The Jewish New Year had occurred two months earlier on Tishri 1, meaning the Hebrews had incremented to King Artaxerxes' 6th year. However, the Egyptians were still in King Artaxerxes' 5th year since Mesore is the 12th Egyptian month. The Egyptian New Year was 35 days in the future from the dated text above.

How do we find out the exact date the above papyrus was written? According to the 5th century BC Egyptian calendar and scholarly references, the Egyptian date of Mesore 1 occurred on November 11. On November 11, the Hebrew lunar date must equal Kislev 21 in Artaxerxes' 6th year. Since the first day of a lunar month happens around a new moon, we know that a new moon had to occur around October 21 in Artaxerxes' 6th year. Artaxerxes became king in August, 465 BC, which means we must consider lunar data from the years 461, 460 and 459 BC, as follows:

In the chart above, a new moon occurred on October 21 only in 460 BC. The lunar alignment of 21 days confirms King Artaxerxes' 6th year for the Hebrew culture. Moreover, this dated text confirms that King Artaxerxes ascended to the Persian throne in August, 465 BC.(10)

The following chart positions November 11, 460 BC, in the 6th Hebrew year; and the 5th Egyptian year for Artaxerxes.

So this papyrus supports the evidence found on the Babylonian Astronomical Text, showing that Artaxerxes' father was murdered in August, 465 BC.(1)(2)

Papyri from the Jewish colony at Elephantine, Egypt allow us to pinpoint specific dates for King Artaxerxes' reign. I have assembled the following chart based on actual double dated papyri from Elephantine, Egypt. All the papyri support the Hebrew counting for King Artaxerxes.

These papyri pinpoint King Artaxerxes' reign. The results show that Nehemiah received the decree to rebuild Jerusalem on Sunday, March 16, 445 BC.
 

Recent scholarship agrees that King Artaxerxes ascended to the throne in August, 465 BC. The following scholarly works support the conclusion of this research.

(1) Cambridge History of Judaism

(2) A Political History of the Achaemenid Empire
 

(1) Sachs, A.J., Pinches, T.G., & Strassmaier, J.N., Late Babylonian Astronomical and Related Texts, Brown University Press, Providence, R.I., © 1955.

(2) Dandamaev, M.A., A Political History of the Achaemenid Empire, E.J. Brill, Leiden, The Netherlands, © 1989, p. 234.

(3) Parker, Richard A. & Dubberstein, Waldo H., Babylonian Chronology: 626 BC - AD 75, Brown University Press, Providence, R.I., © 1956, p. 17.

(4) Thiele, Edwin R., The Mysterious Numbers of the Hebrew Kings, Zondervan Publishing House, Grand Rapids Michigan 49506, © 1983, p 53, 180.

(5) E. J. Bickerman, Chronology of the Ancient World, Cornell University Press, Ithaca, New York, © 1968, p 117.

(6) Herman H. Goldstine, New and Full Moons, 1001 BC to AD 1651, © 1973 by The American Philosophical Society, Independence Square, Philadelphia, p 45.

(7) S. H. Horn & L. H. Wood, "The Fifth-Century Jewish Calendar at Elephantine," Journal of Near Eastern Studies 13 (January 1954), p 8.

(8) Horn, S.H. & Wood, L.H., The Fifth Century Jewish Calendar at Elephantine, Journal of Near Eastern Studies 13 (January 1954): pp 9-10.

(9) Herman H. Goldstine, New and Full Moons, 1001 BC to AD 1651, © 1973 by The American Philosophical Society, Independence Square, Philadelphia, p 45.

(10) Horn, S.H. & Wood, L.H., The Fifth Century Jewish Calendar at Elephantine, Journal of Near Eastern Studies 13 (January 1954): pp 9-10.