Four Post-Exilic Texts
There are four texts in the Hebrew scriptures that were written in close historical proximity: Ezra, Nehemiah, Haggai, and Zechariah 1-8.
In their respective books, Ezra and Nehemiah are portrayed as significant leaders during the post-exilic period, especially regarding the efforts to build a new temple in Jerusalem. Likewise, Ezra mentions Haggai and Zechariah as influential prophets who helped lead and encourage this construction project:
Now the prophets, Haggai and Zechariah son of Iddo, prophesied to the Jews who were in Judah and Jerusalem, in the name of the God of Israel who was over them. (Ezra 5.1, NRSV)
So the elders of the Jews built and prospered, through the prophesying of the prophet Haggai and Zechariah son of Iddo. (Ezra 6.14, NRSV)
Buried in Nehemiah is a reference that Zechariah was also a priest over the community:
In the days of Joiakim the priests, heads of ancestral houses, were: . . . of Iddo, Zechariah . . . (Nehemiah 12.12,16, NRSV)
The implication is that these four texts were closely united in the effort to rebuild Jerusalem and its temple. It's reasonable to infer that their authors were likewise united (to whatever degree) in their views as to what God wanted out of the Jewish community.
Jeshua and Zerubbabel as Leaders of the Returning Jews
If we read these four texts, Ezra, Nehemiah, Haggai, and Zechariah 1-8, we see two names appear together several times: Joshua (also spelled Jeshua), the high priest, and Zerubbabel, a descendant of David and Persia's appointed governor over the repatriated Jews.
Ezra
Ezra repeatedly associates these two men with the construction of Jerusalem and the temple:
They came with Zerubbabel, Jeshua, Nehemiah . . . (Ezra 2.2, NRSV)
Then Jeshua son of Jozadak, with his fellow priests, and Zerubbabel son of Shealtiel with his kin set out to build the altar of the God of Israel . . . (Ezra 3.2, NRSV)
. . . Zerubbabel the son of Shealtiel and Jeshua the son of Jozadak . . . appointed the Levites, from twenty years old and upward, to supervise the work of the house of the LORD. (Ezra 3.8, NRSV)
But Zerubbabel, Jeshua, and the rest of the heads of families in Israel said to them, ‘You shall have no part with us in building a house to our God; but we alone will build to the LORD, the God of Israel, as King Cyrus of Persia has commanded us.’ (Ezra 4.3, NRSV)
Then Zerubbabel son of Shealtiel and Jeshua son of Jozadak set out to rebuild the house of God in Jerusalem . . . (Ezra 5.2, NRSV)
Nehemiah
Jeshua and Zerubbabel's involvement are also implied by Nehemiah:
Now the leaders of the people lived in Jerusalem; and the rest of the people cast lots to bring one out of ten to live in the holy city Jerusalem, while nine-tenths remained in the other towns . . . These are the priests and the Levites who came up with Zerubbabel son of Shealtiel, and Jeshua . . . (Nehemiah 11.1, 12.1, NRSV)
Haggai
Meanwhile, Haggai explicitly states that Jeshua and Zerubbabel had been chosen by God to lead the project:
the word of the LORD came by the prophet Haggai to Zerubbabel son of Shealtiel, governor of Judah, and to Joshua son of Jehozadak, the high priest . . . And the LORD stirred up the spirit of Zerubbabel son of Shealtiel, governor of Judah, and the spirit of Joshua son of Jehozadak, the high priest, and the spirit of all the remnant of the people; and they came and worked on the house of the LORD of hosts, their God . . . (Haggai 1.1,14 NRSV)
Yet now take courage, O Zerubbabel, says the LORD; take courage, O Joshua, son of Jehozadak, the high priest; take courage, all you people of the land, says the LORD; work, for I am with you, says the LORD of hosts . . . (Haggai 2.4, NRSV)
Haggai's Prophecy About Zerubbabel
After highlighting God's will for both Jeshua and Zerubbabel, Haggai then singles out Zerubbabel as the one through whom God would restore Jerusalem:
Speak to Zerubbabel, governor of Judah, saying, I am about to shake the heavens and the earth, and to overthrow the throne of kingdoms; I am about to destroy the strength of the kingdoms of the nations, and overthrow the chariots and their riders; and the horses and their riders shall fall, every one by the sword of a comrade. On that day, says the LORD of hosts, I will take you, O Zerubbabel my servant, son of Shealtiel, says the LORD, and make you like a signet ring; for I have chosen you, says the LORD of hosts. (Haggai 2.21-23, NRSV)
There are three points to keep in mind when reading this prophecy from Haggai to Zerubbabel:
- God has chosen Zerubbabel to be his 'signet ring' (i.e. his royal stamp of authority),
- Zerubbabel was identified as a descendant of David (cf. 1 Chronicles 1.1-19),
- God will dethrone all other kingdoms in relation to the reviving kingdom of Judah.
Zechariah's Prophecy About The Branch
To summarize: Ezra, Nehemiah, and Haggai were largely concerned with the repatriation of the Jews from Babylon, and consequently the reconstruction of Jerusalem and its temple, which would be led by the high priest, Jeshua, and the governor of Judah and descendant of David, Zerubbabel. Haggai places special emphasis on Zerubbabel.
Zechariah 1-2 is a semi-symbolic prophecy concerning the seventy-year exile in Babylon and God's desire for the Jews to return to Jerusalem.
Zechariah 3 symbolically portrays God's appointment of Jeshua to be the high priest and leader during the return from exile. Within this scene, an angel informs Jeshua that God will raise up 'the Branch', which he calls his 'servant'.
Zechariah 4 gives another symbolic vision, this of two olive trees, which explicitly identifies Zerubbabel as the chief leader God has chosen for Jerusalem during the return from exile. Zechariah specifically credits Zerubbabel with initiating the reconstruction of the temple (4.9). The vision of the two trees is interpreted as a union of two God-chosen leaders (4.14), bringing to mind the partnership of Jeshua and Zerubbabel described throughout Ezra, Nehemiah, and Haggai thus far.
Zechariah shows familiarity with prophetic traditions found in Jeremiah, namely the seventy-year exile (Zechariah 1.12; cf. Jeremiah 25.11-12, 29.10) and 'the Branch' (Zechariah 3.8, 6.12; cf. Jeremiah 23.5, 33.15).
Haggai's prophecy about Zerubbabel drew on prophetic ideas associated with David's dynasty and imposed them onto Zerubbabel. When we find Zechariah 3-4 placing immense importance on Jeshua and especially Zerubbabel, we should take note that Zechariah has likewise drawn on prophetic ideas associated with David's dynasty.
Zechariah's Second Prophecy About The Branch
Zechariah mentions 'the Branch' a second time, in chapter 6. In this passage, Jeshua is addressed a second time concerning 'the Branch', mirroring what we saw in chapter 3. Here it is made abundantly clear to the reader that Zerubbabel is 'the Branch'.
The word of the LORD came to me [Zechariah] ... say to him [the high priest Joshua son of Jehozadak]: Thus says the LORD of hosts: Here is a man whose name is Branch: for he shall branch out in his place, and he shall build the temple of the LORD. It is he that shall build the temple of the LORD; he shall bear royal honour, and shall sit and rule on his throne. There shall be a priest by his throne, with peaceful understanding between the two of them. (Zechariah 6.9-13, NRSV)
In this short passage, all the pieces come together. Jeshua has been chosen by God to lead Jerusalem, and he is a partner to 'the Branch'※ whom God has chosen to rule over the people, and this 'Branch' is credited with rebuilding the temple.
Zerubbabel is 'the Branch'.
This is the interpretation taken by Rashi:
whose name is the Shoot: He is Zerubbabel, mentioned above (3:8): “Behold, I bring My servant, the Shoot,” since his greatness burgeoned little by little. Some interpret this as referring to the King Messiah, but the entire context deals with the [time of the] Second Temple.
With his contemporary Haggai, Zechariah seems to have expected a bright future for Judah to come through the efforts of David's descendant (i.e. 'branch') Zerubbabel. With Zerubbabel leading the reconstruction in Jerusalem, Zechariah apparently anticipated for God to revive the kingdom of Judah through Zerubbabel (and Jeshua).
Footnote
※ By this I mean that the passage in Zechariah 6 distinguishes between two individuals: the priesthood as represented by Jeshua, and the royal 'Branch'. Some English translations, especially in verse 13, render 'the priest' and 'the Branch' as one individual. Explicitly Christian translations sometimes capitalize the pronouns 'He' and 'His' to identify this individual as God (i.e. incarnate in the person of Jesus).
My answer here instead follows interpretations / translations that distinguish the priest and the Branch as separate individuals, e.g. the NRSV (provided above), the NET, or The Complete Jewish Bible. This interpretation of the text, distinguishing the priest and the Branch, even goes as far back as the Septuagint:
And it is he that shall receive virtue and and shall sit and rule on his throne. And the priest shall be on his right, and peaceful counsel shall be between the two of them. (New English Translation of the Septuagint)