A day of the trumpet and alarm against the fenced cities, and against the high towers.

Jamieson-Fausset-Brown Bible Commentary

16. the trumpet-namely, of the besieging enemy (Am 2:2).

alarm-the war shout [Maurer].

towers-literally, "angles"; for city walls used not to be built in a direct line, but with sinuous curves and angles, so that besiegers advancing might be assailed not only in front, but on both sides, caught as it were in a cul-de-sac; towers were built especially at the angles. So Tacitus describes the walls of Jerusalem [Histories, 5.11.7].

Matthew Henry's Concise Commentary

1:14-18 This warning of approaching destruction, is enough to make the sinners in Zion tremble; it refers to the great day of the Lord, the day in which he will show himself by taking vengeance on them. This day of the Lord is very near; it is a day of God's wrath, wrath to the utmost. It will be a day of trouble and distress to sinners. Let them not be laid asleep by the patience of God. What is a man profited if he gain the whole world, and lose his own soul? And what shall a man give in exchange for his soul? Let us flee from the wrath to come, and choose the good part that shall never be taken from us; then we shall be prepared for every event; nothing shall separate us from the love of God in Christ Jesus our Lord.