Mat 24:15 "Therefore when you see the 'abomination of desolation,' spoken of by Daniel the prophet, standing in the holy place" (whoever reads, let him understand),"
Regardless of how liberal scholars and doubting theologians now view Daniel, our Lord Jesus proclaimed him a prophet (Matt. 24:15; Mark 13:14). Therefore, we can trust all the prophecies given to Daniel and not the heresies of those faithless theologians.
(Historic events below are taken from commentaries)
Dan 11:1 "Also in the first year of Darius the Mede, I, even I, stood up to confirm and strengthen him."
In the Dan 9:1-2, we see that in the first year of Darius the Mede, Daniel realized how long Jerusalem would remain desolate (70 years), based on the prophecies of Jeremiah. Because of this realization and in accordance with God's instructions in the Torah (Lev 26:40-42), Daniel prayed to God and confessed the sins of his people (Dan. 9:3-19). After doing so, Gabriel was sent to Daniel and gave him the prophecy of the 70 weeks (Dan. 9:24-27), which was the timeline showing when the Messiah would appear in Israel.
Dan 11:2 And now I will tell you the truth: Behold, three more kings will arise in Persia, and the fourth shall be far richer than them all; by his strength, through his riches, he shall stir up all against the realm of Greece."
The mention of Darius the Mede here by Gabriel is not random, but was rather intended to point Daniel (and us) back to this previously specified period of time in order to understand when the prophetic events he is about to outline would occur. Therefore, we can look for the fulfillment of this prophecy within that prophesied 70 x 7(week) years.
This prophecy was given in the third year of Cyrus, king of Persia (c. 535 BCE). The next three Medo-Persian kings after Cyrus were:
1. his son, Cambyses II (530-522 BCE);
2. Gaumata the Magian (also known as the pseudo-Smerdis – 522 BCE); and
3. the Persian Darius I (the Great – 522-486 BCE).
The fourth king was Xerxes (486-465 BCE).
Xerxes' mother was Atossa, the daughter of Cyrus the Great. His father, Darius the Great, left him the task of punishing the Greeks for their part in the Ionian rebellion (499-494 BCE) and their defeat of the Persian army at the battle of Marathon (490 BCE).
Xerxes began extensively preparing for his expedition against the Greeks in 483 BCE by raising money and accumulating provisions. He had a channel dug through the isthmus of the peninsula of Mount Athos, stored supplies along the road through Thrace, and had two bridges constructed across the Hellespont. In preparation to punish the Greeks, Xerxes also entered into an alliance with Carthage. Even many of the smaller Greek states sided with the Persians. A large fleet and a vast army (numbered by some at over two million men) were gathered. He certainly did "stir up all against the kingdom of Greece."
In the spring of 480 BCE, Xerxes set out from Sardis. At first, he was victorious. But when Xerxes attacked the Greek fleet under negative conditions at the Battle of Salamis (September 28, 480 BCE), he lost, even though his fleet was more than three times as large as the Greek navy (1,207 ships to 371).
Xerxes was forced to retire to Sardis, and the army which he left in Greece was annihilated the following year. The Delian League (also known as the Athenian Empire), was formed in 477 BCE as a defensive alliance of the Greek city-states against the Persians.