Dacian King Decebalus. • When Trajan came to power, he invaded Dacia to weaken its threat to Roman border territory. Decebalus was defeated. He remained in power as a client king, but continued to assert his independence, leading to a final and overwhelming Roman invasion in 105. Trajan reduced the Dacian capital Sarmizegetusa in 106, absorbing Dacia into the Empire. Decebalus committed suicide to avoid capture.