Capua first became a state of its own under Landulf I. In 839, the duke of Benevento, Sicard, was killed by Radelchis, who took the throne for himself. This caused a civil war that divided the country. Sicard's brother Siconulf declared Salerno independent and himself prince of Salerno. Landulf and his sons had also been allies to Sicard, so the gastald declared Capua independent too. In 841, Capua was sacked and completely destroyed by mercenaries hired by Radelchis. In early 849, Landulf's eldest son Lando I asked the Holy Roman Emperor to settle the dispute and end the war. The emperor divided Benevento and Salerno into two separate principalities. Capua was made a county of the Principality of Salerno. Since Old Capua had been destroyed, Lando I had a new city built around a nearby fort in 856. This new city was the Capua that still exists today.