Failure to nominate an heir could invite chaotic, destructive wresting of power by a succession of competing claimants – a civil war. Too early a nomination could be seen as an abdication, and reduce the chance for an orderly transmission of power. As Trajan lay dying, nursed by his wife, Plotina, and closely watched by Perfect Attianus, he could have lawfully adopted Hadrian as heir, by means of a simple deathbed wish, expressed before witnesses; but when an adoption document was eventually presented, it was signed not by Trajan but by Plotina, and was dated the day after Trajan's death.
Early in 117, Trajan grew ill and set out to sail back to Italy. His health declined throughout the spring and summer of 117, something publicly acknowledged by the fact that a bronze bust displayed at the time in the public baths of Ancyra showed him clearly aged and emaciated. After reaching Selinus (modern Gazipaşa) in Cilicia, which was afterward called Trajanopolis, he suddenly died from edema, probably on 11 August.
Hadrian relieved Judea's governor, the outstanding Moorish general Lusius Quietus, of his personal guard of Moorish auxiliaries; then he moved on to quell disturbances along the Danube frontier. There was no public trial for the four – they were tried in absentia, hunted down, and killed. Hadrian claimed that Attianus had acted on his own initiative, and rewarded him with senatorial status and consular rank; then pensioned him off, no later than 120. Hadrian assured the senate that henceforth their ancient right to prosecute and judge their own would be respected. In Rome, Hadrian's former guardian and current Praetorian Prefect, Attianus, claimed to have uncovered a conspiracy involving Lusius Quietus and three other leading senators, Lucius Publilius Celsus, Aulus Cornelius Palma Frontonianus, and Gaius Avidius Nigrinus.