What does Acts 12:20 mean?

Herod Agrippa I is the grandson of Herod the Great and king over almost all his territory with the exception of Decapolis. Agrippa makes his home in Jerusalem where he can maintain favorable relations with the Jewish leaders. Although foolish in his youth, when he became king of Judea, Agrippa kept Caligula from installing a statue of himself in the temple; and Agrippa read aloud the Mosaic law to the people. His friendliness with the Jews has made him an enemy of the church; Agrippa arrested and beheaded the apostle James and arrested Peter, whom he would have executed had an angel not rescued Peter from prison (Acts 12:1–11). Now, Agrippa has come to the Roman capital of Caesarea Maritima on the coast of Samaria (Acts 12:19).

We're not told the nature of the conflict between Agrippa and Tyre and Sidon, but the language suggests they argued violently. Tyre and Sidon are two city-states in Phoenicia, north of Galilee. They have good ports and are known for their trading, but the narrow strip between the mountain range and the Mediterranean leaves little farmland. Egypt is well known for its wheat, but Galilee, Samaria, and Judea are closer. "With one accord" suggests the cities had a similar issue with Agrippa and agreed to join forces to present their complaints. Tyre and Sidon are still cities in Lebanon.

"Chamberlain" can also be translated "trusted personal attendant." "Persuaded" probably means bribed.