The reign of Titus was struck by multiple natural disasters, the most severe of which was the eruption of Mount Vesuvius in 79. The surrounding cities of Pompeii and Herculaneum were completely buried under ash and lava. One year later, Rome was struck by fire and a plague. On the military front, the Flavian dynasty witnessed the siege and destruction of Jerusalem by Titus in 70, following the failed Jewish rebellion of 66. Substantial conquests were made in Great Britain under command of Gnaeus Julius Agricola between 77 and 83, while Domitian was unable to procure a decisive victory against King Decebalus in the war against the Dacians. In addition, the Empire strengthened its border defenses by expanding the fortifications along the Limes Germanicus.