Although the crisis of the 3rd century was not the absolute beginning of Rome's decline, it nevertheless did impose a severe strain on the empire as Romans waged war on one another as they had not done since the last days of the Republic. Within the space of a single century, twenty-seven military officers declared themselves emperors and reigned over parts of the empire for months or days, all but two meeting with a violent end. The time was characterized by a Roman army that was as likely to be attacking itself as it was an outside invader, reaching a low point around 258 AD. Ironically, while it was these usurpations that led to the breakup of the Empire during the crisis, it was the strength of several frontier generals that helped reunify the empire through force of arms.