Joel was written during the locust plague, a time of great distress for the people. The prophet sees in the devastation of the locusts an indication of the coming of the day of the Lord. Therefore all must repent with fasting and mourning. With repentance, however, there is a promise of relief and God’s blessing for Israel.

Joel 2

2:7 They shall run like mighty men; they shall climb the wall like men of war; and they shall march every one on his ways, and they shall not break their ranks: