The Time Traders

The first novel in the classic series, in which wars are no longer fought on land, in the air, or on the sea-but throughout time and space itself ...
The never-ending tension between Russia and the United States has been escalated by a stunning new variable: time travel. While the Americans can roughly utilize the technology, the Russians have learned the secret of space travel-and that makes the US vulnerable. What they need is someone expendable to send through time to obtain the same secret.

Ross Murdock doesn't consider himself expendable. He's just a smart guy who made some bad choices that led him to a life of crime. But when he's given a choice between medical "rehabilitation" and joining the mysterious Operation Retrograde, he decides to go along with the military option and hope for a chance to get away.

And he is going to get away-farther away than he ever imagined ...
The Time Traders is the first book in the Time Traders Series, but you may enjoy reading the series in any order.