Many historians believe he was the victor at the Battle of Boju in 506 BC. The great historian Sima Qian (145/135–86 BC), author of "Shiji" (Historical Record), called Sun Tzu an exceptional strategic battlefield commander. He also said Sun Tzu was both flexible and had unlimited surprises for his enemies. Sima Qian wrote that in his nearly 40-years as a general, Sun Tzu never lost a battle, a campaign or a war.