I'm looking for a novel or novelette written in the late 50's early 60's where a reporter is sent to investigate phenomena at some Indian mounds and a storm approaches and in the storm he is transported back to I believe the Roman era where he's a prisoner oarsman on a ship.
You may be thinking of Lest Darkness Falls; I don't remember the author. I remember reading it many years ago, the man was transported back in time to the Roman era and helped to defeat Rome's enemies. He was able to build a telegraph line to warn of attacks. He wanted to stop the Dark Ages from occurring; hence the Darkness in the title. Hope this helps.