After overthrowing the Parthian confederacy, the Sassanid Empire that arose from its remains pursued a more aggressive expansionist policy than their predecessors and continued to make war against Rome. In 230 AD, the first Sassanid emperor attacked Roman territory first in Armenia and then in Mesopotamia but Roman losses were largely restored by Severus within a few years. In 243 AD, Emperor Gordian III's army retook the Roman cities of Hatra, Nisibis and Carrhae from the Sassanids after defeating the Sassanids at the Battle of Resaena but what happened next is unclear: Persian sources claim that Gordian was defeated and killed in the Battle of Misikhe but Roman sources mention this battle only as an insignificant setback and suggest that Gordian died elsewhere.