Habakkuk wrote his book during a Sabbatical year. The Sabbatical year in question ran from Saturday, September 10 in 627 B.C. to Thursday, September 28 in 626.
[List of Biblical Jubilee Years!]
Old Testament Faith
Surprisingly, the English word faith appears only twice in the entire King James Old Testament! It is only recorded in the books of Deuteronomy and Habakkuk.
And he said, I will hide my face from them, I will see what their end shall be: for they are a very froward generation, children in whom is no faith (Deuteronomy 32:20).
Behold, his soul which is lifted up is not upright in him: but the just shall live by his faith (Habakkuk 2:4).
The Apostle Paul, a fervent supporter of the teaching that those who are called and chosen should center their lives around faith, quoted Habakkuk at least three times.
For therein is the righteousness of God revealed from faith to faith: as it is written, The just shall live by faith (Romans 1:17).
But that no man is justified by the law in the sight of God, it is evident: for, The just shall live by faith (Galatians 3:11).
Now the just shall live by faith . . . (Hebrews 10:38).
[Old Testament Quotes in the Gospels!]
Other New Testament References
As stated above, the Apostle Paul directly quoted Habakkuk 2:4 in three separate writings (Romans 1:17, Galatians 3:11 and Hebrews 10:38). He also, while preaching in Pisidian Antioch during his first missionary journey, quoted the prophet in his closing remarks to a local synagogue.
Beware therefore, lest that come upon you, which is spoken of in the prophets; Behold, ye despisers, and wonder, and perish: for I work a work in your days, a work which ye shall in no wise believe, though a man declare it unto you (Acts 13:40 - 41 referring to Habakkuk 1:5).
[Map of Paul's First Missionary Journey]
Many of the Jews who heard Paul's synagogue message rejected his teachings and warning. There were several others, however, who liked what they heard and asked him to preach again the next Sabbath. These early believers became the basis for the first Christian church in Pisidian Antioch (see Acts 13:42 - 49).
Myths and Legends
The complete lack of personal information about Habakkuk has led to various legends concerning the prophet. One myth identifies him as the resurrected son of a Shunammite woman brought back to life by Elisha (2Kings 4:18 - 37). Another, connecting Habakkuk 2:1 to Isaiah 21:6, proports that he was the watchman set by Isaiah to watch for the fall of Babylon.
One of the strangest legends centering on Habakkuk is found within what is called the deuterocanonical books in Roman Catholic Bible translations. This collection of writings is also labeled the Apocrypha by Protestants. These additions (Tobit, Judith, 1 and 2 Maccabees, etc.) have been determined to be uninspired. They are not found in widely used translations such as the KJV, NKJV, NIV and many others.

It is in Daniel 14 (a deuterocanonical added chapter also labeled as the story of Bel and the Dragon) that we find Habakkuk mentioned. The story is that while the prophet is carrying food he is confronted by an angel. The angel then miraculously takes him to Daniel in the lion's den so that he can give him food to eat. Habakkuk is then miraculously whisked back home.
[Miracles of Old Testament Prophets]
[How Are Catholic Bibles Different?]
Now there was in Jewry a prophet, called Habbacuc (Habakkuk), who had made pottage, and had broken bread in a bowl, and was going into the field, for to bring it to the reapers.
But the angel of the Lord said unto Habbacuc, Go, carry the dinner that thou hast into Babylon unto Daniel, who is in the lions' den . . . Then the angel of the Lord took him by the crown, and bare him by the hair of his head, and through the vehemency of his spirit set him in Babylon over the den (Daniel 14:33 - 34, 36).
Chronologically speaking, Habakkuk's supposed encounter with Daniel is highly doubtful. The prophet wrote his book in 626 B.C. while Daniel was thrown to the lions in, or shortly after, 539 B.C. at least 87 years later!
The Babylonian Empire
Habakkuk, in his first chapter, mentioned that the Chaldeans (Babylonians) would be raised up to fulfill God's will.
[Map of Babylonian Empire at its Peak]
For, lo, I raise up the Chaldeans, that bitter and hasty nation, which shall march through the breadth of the land, to possess the dwelling places that are not theirs (Habakkuk 1:6).
It was in 626 B.C., the same year the prophet likely wrote his book, that Babylon's King Nabopolassar took the throne. His reign, which lasted until 605, would catapult the Babylonians into a world empire.
Nabopolassar's victory over the Assyrian capital of Nineveh in 612 B.C. firmly solidified the power of the Chaldeans. In 605 he defeated the mighty Egyptian army under Pharaoh Necho II at the battle of Carchemish.
Babylon, ruled by Nebuchadnezzar starting in 605 B.C., would ultimately fulfill God's will mentioned in Habakkuk by punishing the unrepentant Kingdom of Judah. Nebuchadnezzar's three attacks, the last of which was in 586 B.C., resulted in the Jews being taken out of the land as captives. He had the city of Jerusalem destroyed and its magnificent temple burned to the ground.
[Ranking of Ancient World Empires]
The empire reached its peak around 560 B.C. when it controlled 193,051 square miles (500,000 square kilometers) of land. It ended in 539 when the Medo-Persians replaced them as a world power.