The hinge of the whole period is one man: Antiochus IV, who styled himself Epiphanes ("the Illustrious") and reigned over the Seleucid (Syrian) empire from 175 to 164 BC. The ISBE describes him as "a typical eastern ruler of considerable practical ability," raised partly as a hostage in Rome, and fanatically devoted to spreading Greek culture (ISBE, "Antiochus IV"). Jerusalem's own leaders gave him his opening: rival aristocrats bought the high priesthood from him and competed to out-Hellenize one another (the ISBE traces how Jason ousted Onias III, then was himself outbid, 2 Maccabees 4). When a rumor of Antiochus' death set off fighting in Jerusalem, the king treated it as revolt.
In 167 BC Antiochus moved to destroy the Jewish religion outright. He plundered the temple, banned circumcision, the Sabbath, and the Scriptures on pain of death, and, the unforgettable sacrilege, set up a pagan altar (to Olympian Zeus) on the great altar of the temple and had swine sacrificed on it (ISBE, "Asmoneans," summarizing 1 Maccabees 1; the ISBE's "Antiochus IV" entry adds the substitution of "the worship of the Olympian Zeus"). This is the desecration the book of Daniel names the "abomination that maketh desolate" (Daniel 11:31; 8:11–13; 9:27), the phrase Jesus himself would later borrow (Matthew 24:15; Mark 13:14). For the first time in their history the Jews faced not just conquest but a deliberate, state-run attempt to erase their faith. It could not stand unanswered.