What does Daniel 11:11 mean?

This is part of a series of predictions given by an angel to the prophet Daniel in 536 BC (Daniel 10:1; 11:2). After accurately predicting the rise and fall of Alexander the Great, the angel described the conflicts between two succeeding nations (Daniel 10:5–9). Ultimately, a revived Seleucid Empire pushed back against Ptolemaic Egypt as far as the modern-day Gaza Strip in southern Israel (Daniel 11:10).

History depicts Ptolemy IV Philopator as lazy, ineffective, and uninspiring. However, as Antiochus the Great's army came closer to Egypt's home territory, Philopator assembled a massive collection of new troops. This seems to be the meaning of the "king of the south"—Philopator—being angry and moved to fight back. His newly trained forces met those of Antiochus in 217 BC in what is today called the city of Rafah. This "Battle of Raphia" or "Battle of Gaza" was among the biggest clashes of the era, and surprisingly ended in a decisive victory for Egypt. As further predicted, the result was many thousands of Seleucid troops killed (Daniel 11:12).

This would not end Antiochus's aggressions. Ptolemy IV Philopator continued to prefer pleasure over leadership, and the newly trained Egyptians who made up much of his recent army gained enough confidence to rebel. Eventually, Antiochus the Great would push Ptolemaic Egypt out of Judea entirely (Daniel 11:13).

For his part, Ptolemy seems to have let the victory go to his head, as following verses will also show.