King Nabis of Sparta was the last remarkable king in the history of Sparta, having fought his wars and pushed his reforms in the backdrop of the first war between the Roman Republic and Macedon, after the former spectacularly defeated Carthage. He allied himself to the Roman side and against Macedon, but his focus was on southern Greece against the Achaean League. After Rome made peace with the Macedonians and Achaeans in 200 BC, however, the consul commanding the Roman armies in Greece, Titus Quinctius Flamininus, persuades by the Achaeans, betrayed Nabis and invaded the Peloponnese, defeating the Spartans and reducing them to Lacaedemon proper from their previous conquests. Nabis later made a second try at empire in 192 BC, allying himself with the Seleucid king Antiochus III in war against Rome, but was then promptly defeated again and murdered. Afterwards, Sparta practically disappeared from history as an independent actor in the Greek world. But what if the Romans had decided to trust and spare Nabis instead, thus preserving Sparta and its newly acquired possessions in southern Greece as a buffer state or client of Rome? Would Nabis or a later king still end up betraying Rome? If not, then does a Roman-Spartan alliance have any lasting effect on the history of the Mediterranean?