Yud Tes Kislev and Chanukah were two dates on which there was a Magbis. At one point, the Rebbe combined the two into one. The Rebbe once said (Zos Chanukah 5739) that one of the reasons for the farbrengen he was holding was to talk about the Magbis of Yud Tes Kislev and Chanukah. The Rebbe referred to the Letter of The Alter Rebbe (Iggeres Hakodesh, end of Letter 4) in which he connects tzedaka to the liberation. The Rebbe also mentioned that which is quoted by Reb Nechemia of Dubrovna (see Sefer Haminhagim p.71), that it is customary to increase tzedaka giving on Chanukah.