Excerpts from Books and Wikipedia
"Isaiah is called the messianic prophet because he was so thoroughly imbued with the idea that his nation was to be a nation through whom one day a great and wonderful blessing would come from God to all nations: the Messiah, sent from God, who would bring peace, justice, and healing to the whole world. . . . Isaiah was a prophet of the southern kingdom, Judah, at the time the northern kingdom, Israel, had already been destroyed by the Assyrians. . . . We may tentatively place his active ministry at about 740-700 B.C." [Halley's Bible Handbook, p. 339] "And he shall judge among the nations, and shall rebuke many people: and they shall beat their swords into plowshares, and their spears into pruninghooks: nation shall not lift up sword against nation, neither shall they learn war any more." [King James Bible, Isaiah 2:4] Shortly after King Sargon's death in 705 B.C.E., Hezekiah was approached by Assyria's vassal king in Babylonia, Merodach-baladan, who was nurturing thoughts of sedition. In the Bible, Hezekiah invites him to Jerusalem to show him the house and its precious things . . . The Bible describes how this state visit alarms the Prophet Isaiah . . . A contemporary of Micah, Isaiah had a vision at age 25, during the last year of King Uzziah's reign, of YHWH calling him to service. From that moment, he embarked on a long career as a prophet, diplomat, and poet, serving three kings as councilor . . . " [Isbouts: Biblical World, p. 219-20]