Before their face the people shall be much pained: all faces shall gather blackness.

          They shall run like mighty men; they shall climb the wall like men of war; and they shall march every one his ways, and they shall not break ranks; neither shall one trust another; they shall walk every one in his path; and when they fall upon the sword, they shall not be wounded.

                  They shall run to and fro in the city; they shall run upon the wall, they shall climb up upon the houses; they shall enter in at the windows like a thief.

                           The earth shall quake before them the heavens shall tremble; the sun and the moon shall be dark, and the stars shall withdraw their shining.   Joel 2:4-10

There are things in this prophecy that makes us doubt that an invasion of literal horsemen is not meant.

       Horses do not climb walls or climb up upon roofs or enter windows like a thief.

       These are spirit beings as demons, looking more like locusts but not literal locusts; but scorpion locusts that John described.