The Previous Rebbe wrote, "Yud Kislev marks the birth of a
chassid, and
Yud-Tes Kislev is the
bris (circumcision)." (
Likkutei Dibburim, p. 976; more info
here)
There are nine days between
Yud Kislev and
Yud-Tes Kislev. On
Yud Kislev we celebrate the liberation of the Mitteler Rebbe, the 2nd Lubbavitcher Rebbe, which also marks the date of his birth and
yahrzeit (9th of Kislev).
Yud-Tes Kislev is the liberation of the Alter Rebbe, the 1st Rebbe, as well as the
yahrzeit of his teacher, the Maggid of Mezeritch.
There are nine days between
Gimmel Tammuz and
Yud-Beis/Yud-Gimmel Tammuz, which is today. On
Gimmel Tammuz, we celebrate the beginning of the liberation of the Previous Rebbe, the 2nd-to-last Lubavitcher Rebbe, which also marks the
yahrzeit of the last Rebbe.
Yud-Beis/Yud-Gimmel Tammuz marks the complete liberation of the Previous Rebbe, as well as his birthday.
When the Previous Rebbe had his bar mitzvah, his father, the Rebbe Rashab, made a seven-day celebration like that
of a wedding (
sheva brachos). Therefore, perhaps we can say as follows, "
Gimmel Tammuz marks the wedding of a
chassid, and
Yud-Beis/Yud-Gimmel Tammuz is the
sheva brachos."