Florence Squad: The Death Merchant

From "The Death Merchant (TTT episode)" (The Time Tunnel) summary on Irwin Allen Wiki

Master Benedict and Brother Michael are sent back in time, landing during the Battle of Monaco during the Florentine Wars. A blast from a cannon goes off right by Benedict, and, once Michael asks for a nearby medic, Benedict is pronounced dead at the scene. At Project Hourglass, it is confirmed that Michael is the only signal being detected out of the two Church knights.

Michael is convinced by a major to leave Benedict behind for the time being and to assist him in tracking the enemy. The major also has Michael change into a Church uniform (even though as Michael said, he is not a soldier).

Meanwhile, personnel at Project Hourglass try a rare power surge to bring Benedict back to life. It succeeds, but unfortunately he has no memory of who he is. Since he was revived next to a crashed courier's ship, he is assumed to be a Legion officer, and dons such uniform to go about his newfound duties as a soldier, tracking down the enemy.

Meanwhile Michael and the Church major track down a mysterious man named Michaels (who was briefly seen earlier with a large dog, being totally out of place, not wearing a uniform from either side, but a black cape) to his cabin, who has stolen a large amount of laser crystals, which must be recovered. He allows Michael and the major inside, but turns the tables on them, severely wounding the major and disarming Michael. Michael is able to talk Michaels into letting him take the major into a storage room to try to care for him but the major passes away. Michael then finds a trunk that is marked as Makerville, a philosopher and writer who died 300 years ago. Michaels claims that he is from another time. Michael (and the Project Hourglass personnel) surmise that the Time Portal was the cause for sending Makerville into the future.

Benedict then appears, and Michael, after being unable to convince Benedict that they are allies, is able to flee the cabin, but Makerville sends his dog after him. Project Hourglass then sends the dog back to his own time, but it causes an explosion and it is estimated that it will take hours for them to restore operations. Benedict tracks down Michael, who tries to talk some sense into Benedict, but he takes Michael back to Makerville, who is going to lead Benedict and Michael to the hidden crystals.

Benedict and Michael get into another fight at the scene when Michael threatens to ignite the crystals, then Benedict finally gets his memory back. Makerville then lights the crystals himself when Michael threatens that he will not get to enjoy the final battle (since, for the entire time, Makerville has just been enjoying himself and causing Benedict and Michael to square off against each other) as Project Hourglass tries to time-shift the Church knights away.