S. M. Stirling The Winds of Fate

Artorius and his team must race against time to thwart a looming clash between two ancient powers, navigating a treacherous landscape where their actions could rewrite history and spark a catastrophic conflict. In a world where history can be rewritten at will, the threads of destiny intertwine in ways no one could have foreseen. Years after their groundbreaking journey into the past, the Harvard professor now dubbed "Artorius" and his team of grad students stumble upon a devastating revelation: the Chinese government has dispatched five time-travelers and a trove of advanced technology back to 165 CE, during the waning days of the Han dynasty. The team believed they were guiding Rome toward a new era of modernization and unity, but the emergence of Chinese influence threatens to unravel everything they have fought for. As whispers of innovation ripple through the ancient world, Artorius and his companions realize they are in a race against time--not just to protect their vision for a united future, but to prevent a catastrophic clash that could bring about nuclear war centuries sooner than they ever imagined. With their own presence now at risk of exposure, they must navigate the treacherous waters of politics, technology, and culture in a world caught between two colossal powers. As the balance of history teeters on a knife's edge, loyalties will be tested, alliances forged, and the very fabric of fate will hang in the balance.