During the Chmielnitzki Massacres (see entry for 4 Sivan), a Cossack mob gathered around the fortified town of Olyka. Among the Jews who had found refuge inside was R. David Halevi (the Taz), a refugee from the nearby city of Ostroh. As the Cossacks prepared to breach the walls, the Jews gathered in prayer in the synagogue. Weak and tired, R. David drifted off to an uneasy sleep, and in his dream he envisioned the verse, “I will protect this city to save it, for My sake and for the sake of My servant David” (II Kings 19:34). Indeed, the old cannons atop the walls miraculously fired spontaneously toward the enemy, who proceeded to flee (Minhagei Beis Alik, p. 752).
Link: Jews in Eastern Europe
This Shabbat is Shabbat Mevarchim (“the Shabbat that blesses" the new month): a special prayer is recited blessing the Rosh Chodesh ("Head of the Month") of the upcoming month of Tammuz, which falls on Wednesday and Thursday of the coming week.
Prior to the blessing, we announce the precise time of the molad, the "birth" of the new moon. See molad times.
It is a Chabad custom to recite the entire book of Psalms before morning prayers, and to conduct farbrengens (chassidic gatherings) in the course of the Shabbat.
Links: Shabbat Mevarchim; Tehillim (the Book of Psalms); The Farbrengen
During the summer months, from the Shabbat after Passover until the Shabbat before Rosh Hashahah, we study a weekly chapter of the Talmud's Ethics of the Fathers ("Avot") each Shabbat afternoon; this week we study Chapter Three.