the chronology of the makkos and the mitzvah of kiddush ha'chodesh

Apologies for writing a bit b'kitzur this week.

The challenge of figuring out the chronology of the makkos is getting three facts to fit together:

1) The mishna in Ediyot that tells us that the judgment of the Mitzrim took place over one year.

2) The gemara in Rosh haShana tells us that the shibud let up on Rosh haShana

3) Rashi quotes from Chazal that each makkah lasted a week after which there was a three week break = 1 month in total.

10 makkos of 1 month each = 10 months, not a year, so what do you do with the mishna in Ediyot?  If the makkos forced the Mitzrim to end the shibud, then shouldn't Pesach coincide with Rosh haShana, since acc to the gemara in R"H that is when slavery ended?  The facts at hand seem to contradict each other.

One approach is that of Tos/Maharasha in Rosh haShana.  According to this view, Moshe came to Pharoah in Nissan, but the Egyptians continued to subjugate the Jews, despite their being hit with makkos.  The forced labor of shibud only ended on Rosh haShana, and culminated with total freedom being granted in Nissan.  Even though each makkah took 1 month to run its course, the makkos did not follow back to back -- there was a gap of a few days between them, so that 10 makkos were spread over 12 months in total.

Ramban has a different view.  He writes in our parsha that the last three makkos all took place in Nissan.  Barad destroyed the early blossoms on the trees in Adar, but the trees themselves were still unharmed until arbeh came and finished them off in Nissan.  (According to Tos view that the makkos were at least a month long, barad would have to have happened in Teives.  Teivis is in the middle of winter and nothing is growing, so what crops and blossoms could have been destroyed?)  Chasam Sofer explains that according to this view, the makkos began on Rosh haShana, and that is what forced the Egyptians to terminate the shibud then.  The idea of the judgment of the Mitzrim taking a full year (the mishna in Ediyot) is counting from the first time Moshe came before Pharoah, not from the start of the makkos.  How do you fit 7 makkos in the 6 months between R"H and Nissan?  Chasam Sofer answers that it must have been a leap year, and so there would have been seven months in between those dates.

This Chasam Sofer puzzles me.  The reason we have a leap year is in order to keep the lunar and solar calendars in sync.  More specifically, because there is a din that Pesach must fall out in "chodesh ha'aviv," the spring.  If you have a lular calendar that is not synced with the solar calendar by adding leap months (e.g. if I am not mistaken, this is the calendar of the Islamic religion), then lunar months can drift between different seasons.  By adding a leap month approximately once every three years, we ensure that Nissan is always in the spring.  What sense does any of this make before yetzi'as Mitzrayim has happened, before we have been commanded "shamor es chodesh ha'aviv" to make sure to celebrate Pesach in the spring?!  Chasam Sofer is disussing the chronology of the year prior to yetzi'as Mitzrayim.  There is not yet a holiday of Pesach to schedule in any season, so why should there have been any concern about keeping the two calendars, lunar and solar, in sync?

If someone has a better approach, I would appreciate hearing it, but here is my thought: Had you asked me, I would have said that before we were given the mitzvah of kiddush ha'chodesh, there was no such thing as a halachic calendar.  We could have followed the Mayan calendar, the Chinese calendar, the Julian calendar, or made up something from scratch.  However, this does not seem to be the case.  There is a Pirkei d'Rabbi Elazar (ch 8) which writes that the sod ha'ibbur was given to Adam haRishon:

בְּעֶשְׂרִים וּשְׁמוֹנֶה בֶּאֱלוּל נִבְרְאוּ חַמָּה וּלְבָנָה. וּמִנְיָן שֶׁהוּא שָׁנִים וְחֳדָשִׁים וְיָמִים וְלֵילוֹת שָׁעוֹת וְקִצִּים וּתְקוּפוֹת וּמַחְזוֹרוֹת וְעִבּוּרִין הָיוּ לִפְנֵי הַקָּדוֹשׁ בָּרוּךְ הוּא, וְהָיָה מְעַבֵּר אֶת הַשָּׁנָה וְאַחַר כָּךְ מְסָרָן לְאָדָם הָרִאשׁוֹן בְּגַן עֵדֶן, שֶׁנֶּאֱמַר (בראשית ה, א): ״זֶה סֵפֶר תּוֹלְדֹת אָדָם״, מִנְיַן עוֹלָם לְכָל תּוֹלְדוֹת בְּנֵי אָדָם.

And it was then passed b'mesorah until it got to the Avos.  So there was a halachic calendar, with leap years, etc. even before the mitzvah of kiddush ha'chodesh was given.  What then was the chiddush of the mitzvah?  I think what you have to say is that the mitzvah did not create the calendar we use, but rather the chiddush of the mitzvah is that we, Klal Yisrael, have been granted control over the calendar.  Whether there will be a leap year or not is entirely up to us to decide.  The mitzvah empowered us as a people, which is the first step in the transition from slavery to freedom.  It is that idea of empowerment which is why this mitzvah is in our parsha, as part of the story of yetzi'as Mitzrayim.