a day of horn blast and battle cry against the fortified cities, and against the high corner towers.
Nothing could be expressed with more spirit and life, nor in words more proper to startle and awaken a secure and careless people, than the warning here given to Judah and Jerusalem of the approaching destruction by the Chaldeans. That is enough to make the sinners in Zion tremble - that it is the day of the Lord, the day in which he will manifest...
Commenting on Zephaniah 1:14-18
A day of the trumpet and alarm against the fenced cities, &c.] The trumpet of the enemy, sounding the alarm of war against the fenced cities of Judea, which were taken before Jerusalem; calling and gathering the soldiers together, and animating them to the assault of them; and blowing them in a way of triumph; and as expressive of victory, having got possession of them...
the trumpet--namely, of the besieging enemy (Amo 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].