On the Shabbat before the Exodus--Nissan 10th on that year--the first-born of Egypt, who occupied the senior positions in the priesthood and government, fought a bloody battle with Pharaoh's troops, in an effort to secure the release of the Israelites and prevent the Plague of the Firstborn. This "great miracle" is commemorated each year on the Shabbat before Passover, which is therefore called Shabbat HaGadol, "The Great Shabbat." (This is one of the rare instances in which a commemorative date in the Jewish calendar is set by the day of the week rather than the day of the month.)
For more on the war of the Firstborn, see here.
Miriam, the sister of Moses, passed away at the age of 126 on the 10th of Nissan of the year 2487 from creation (1274 BCE) -- 39 years after the Exodus and exactly one year before the Children of Israel entered the Holy Land. It is in deference to her passing that the "Great Shabbat" is commemorated on the Shabbat before Passover rather than the calendar date of the miracle's occurence, Nissan 10.
Link: About Miriam.
Three days after the two spies dispatched by Joshua scouted the city of Jericho (see entry for "Nissan 7" above), the children of Israel were ready to enter the land promised by G-d to their ancestors as their eternal heritage. As they approached the Jordan with the Holy Ark carried by the Kohanim (priests) in their lead, the river parted for them, as the waters of the Red Sea had split when their fathers and mothers marched out of Egypt 40 years earlier. (Joshua 4)
In today's "Nasi" reading (see "Nasi of the Day" in Nissan 1), we read of the gift bought by the nasi of the tribe of Dan, Achiezer ben Amishadai, for the inauguration of the Mishkan.
The Shabbat before Passover is termed Shabbat HaGadol ("The Great Shabbat") in commemoration of the "great miracle" that happened in Egypt on this day, heralding the Exodus from Egypt five days later (see "Today in Jewish Hstory"). Shabbat HaGadol customs include reading a portion of the Haggadah (from "Avadim hayinu..." to "...al kol avonotainu"), which tells the story of the Exodus; it is also customary that the rabbi of the community delivers a lecture in which he elaborates on the laws of Passover and their significance, in preparation for the festival.
In the month of Elul, the month before Rosh Hashanah, a signal goes out to every Jewish soul that it is time to return to the palace that is home.
It is a signal both subtle and loud.
Subtle, because it does not awaken even those who are closest—every soul must awaken itself. Loud, because it reaches those who have been thrown to the edge of the universe.
Loud, because it is a signal of love and joy. Subtle, because it is an intimately personal call.
Loud, because it provides immeasurable powers to break out of whatever holds you back, lift you above all obstacles, and carry you all the way home. Subtle, because the power is there, but latent, quiet, awaiting your determination.
How can a signal be both subtle and loud, joyful and intimate, empowering and latent?
Because this signal originates from the very origin of your own soul, that place from which your soul was torn but has never truly abandoned. And as distant as a soul may stray, as lost as she may be, she will always remain one with her Beloved.
And now she hears her Beloved call, from a place deep within herself.