One of the most famous units of the ancient world were the macedonian pikes, which the romans met and defeat in their conquest of the Eastern Mediterranean.
My question is, did the Romans ever deployed armies that used the pike phalanx formation? I reckon emperor Caracalla equiped some of eastern legions with pike as he was a great admirer of Alexander the Great, so this make me believe the formation was not unknown to the Romans, but I don't know if they ever fought like that. And if they would be effective.
It doesn't need to be the legions, maybe auxiliaries troops? Or the units of the Late and then only Eastern Empire? Do we know anything about that?
Gratitude.
Pike phalanxes were not standard infantry, but were adopted numerous times, often when fighting cavalry-heavy armies from the east.
In preparation for his Parthian campaign Caracalla ordered 16,000 men to be trained in Macedonian drill and fight in a phalanx. Severus Alexander also had elements of six legions formed into phalangiarii, who fought in a phalanx.
Arrian of Nicomedia, during his campaign against the Alani, used pike phalanxes to ward off the Alani cavalry.
From Arrian's "Extaxis contra Alanos"
(Section 15) The infantry should be drawn up eight ranks deep, in a closely packed formation. (Section 16) The first four ranks shall consist of pike-bearers, whose pikes will end in long, slender iron points. The men in the first rank should hold their pikes at the ready, so that if the enemy comes near, they can thrust the iron tip of their pike especially at the breasts of the horses. (Section 17) The men of the second (?), third, and fourth ranks should hold their pikes forward to jab and wound the horses where they can, and kill the riders.