Since this verse begins a new subsection, it may be helpful to begin with the quote frame “Ezra said” (Contemporary English Version) to remind the reader that Ezra is still speaking here.

We departed from the river Theras on the twelfth day of the first month: For the river Theras, see verse 41; for the first month, see 1 Esdras 8.6.

And we arrived in Jerusalem by the mighty hand of our Lord which was upon us means God’s power protected Ezra’s group during their travels, enabling them to arrive safely in Jerusalem. For the mighty hand of our Lord, see the comments on verses 47-48. The journey from Theras Canal to Jerusalem was about 1,300 kilometers (800 miles).

He delivered us from every enemy on the way, and so we came to Jerusalem: This sentence repeats many of the ideas in the previous one, but adds the idea of God protecting them from enemies. The conjunction so does not appear in the Greek text, but is a good way of bridging the brief account of the journey and the statement that they arrived in Jerusalem.

Good News Bible provides a good model for this verse. Contemporary English Version is also helpful with the following model:

• Ezra said:
On the twelfth day of the first month, we left the Theras River and started for Jerusalem. Our God watched over us all the way to Jerusalem, and as we traveled along he rescued us from our enemies.

Quoted with permission from Bullard, Roger A. and Hatton, Howard A. A Handbook on 1-2 Esdras. (UBS Helps for Translators). Miami: UBS, 2019. For this and other handbooks for translators see here.