"From the greatness of the crisis and the solemnity of the warning, these emissaries must be creatures of awesome power. Yet they seem unaccountably crude, uncouth, and unseemly. They surprise us. “Frogs!” we exclaim, “heralds of battle? Ambassadors to kings? Impossible! Absurd! Ridiculous!” The crisis is the greatest in the annals of war. It is referred to in scripture, as well as in our text, as “the battle of that great day of God Almighty.” It is portrayed as a World War, a Universal Conflict. And yet — to assemble the militant nations — three slimy batrachian monsters! What are these “questionable shapes,” these disgusting amphibia, from the swamps and mud of dried-up Euphrates? John describes them as “unclean spirits,” they are “demons,” or dead men. What we see in the vision is three ghostly emissaries, one out of the mouth of each of the confederates, the dragon, the wild beast, and the false prophet — gigantic shadowy frogs, croaking night prowlers, cold-blooded reptiles dwelling in marshes, quagmires, and stagnant waters, with their spotted skin, their sprawling limbs, their agile leap, their dismal croakings filling the night with noise. They are as politicians, these masqueraders, at home in the slimy pool, in the gooey mud, in the air or on solid ground; noisome, repulsive, abhorrent. Of what are these cheap orators, these uncanny imposters the emblem?"

Much more in the text:

https://www.godfire.net/eby/rev185.html