His subjects discovered—to their astonishment—that they too had been bequeathed to the Roman Empire.

From War! What Is It Good For? by Ian Morris. Page 51.

The most peculiar stories may be those of Ptolemy VIII (nicknamed Fatso) and Attalus III, kings of Egypt and Pergamum, respectively. Ptolemy had been kicked out of Egypt by his brother (also named Ptolemy) in 163 B.C., and in 155 B.C. the dispossessed Ptolemy drew up a will leaving his new kingdom of Cyrene to the Roman people if he died without heirs.
Attalus, though, went further; he actually did die without heirs in 133 B.C., whereupon his subjects discovered—to their astonishment—that they too had been bequeathed to the Roman Empire.

We do not know how the Romans felt about Ptolemy’s will, since the overweight monarch in fact lasted another four decades and, after seducing his own stepdaughter, left rather a lot of heirs. We do know, though, that the Romans were as surprised as the Pergamenes by Attalus’s bequest, and with self-interest strongly to the fore, competing factions in the senate fell into heated arguments over whether Attalus actually had the right to give his city to them.

Ptolemy and Attalus did what they did not because they loved Rome but because they feared it less than they feared war. Lacking heirs, both men dreaded civil war. The brothers Ptolemy had already tried fratricide and gone to war even before Fatso drew up his will, and Attalus’s position was worse still. A pretender to the throne, claiming to be Attalus’s half brother, was stirring up revolt among the poor (and might have begun a civil war even before Attalus died), and four neighboring kings were waiting in the wings to dismember Pergamum. No wonder a bloodless Roman takeover looked good to both kings.