Year 217 BC was a year of the pre-Julian Roman calendar. At the time it was known as the Year of the Consulship of Geminus and Flaminius/Regulus. The denomination 217 BC for this year has been used since the early medieval period, when the Anno Dominicalendar era became the prevalent method in Europe for naming years.
Quintus Fabius Maximus begins his strategy of "delay". This involves avoiding a set battle with the Carthaginians and creating a "scorched earth" area around Hannibal's army. Manoeuvring among the hills, where Hannibal's cavalry is ineffective, Fabius cuts off his enemy's supplies and harasses Hannibal’s forces incessantly. Fabius gains the name Cunctator for this strategy.
Hannibal ravages Apulia and Campania; meanwhile the delaying tactics of Quintus Fabius Maximus' army allows only skirmishes to occur between the two armies.
Fabius' delaying policy becomes increasingly unpopular in Rome, and Fabius is compelled to return to Rome to defend his actions under the guise of observing some religious obligations. Marcus Minucius Rufus, the master of horse, is left in command and manages to catch the Carthaginians off guard near their camp in Geronium and inflicts severe losses on them in a large skirmish. This "victory" causes the Romans, disgruntled with Fabius, to elevate Minucius to the equal rank of dictator with Fabius.
Minucius takes command of half the army and camps separately from Fabius near Geronium. Hannibal, informed of this development, lays an elaborate trap, which draws out Minucius and his army and then Hannibal attacks it from all sides. The timely arrival of Fabius with the other half of the army enables Minucius to escape after a severe mauling. After the battle, Minucius turns over his army to Fabius and resumes the duties of Master of Horse.
Egypt
June 22 - Egyptian native hoplites under Ptolemy IV crushes the Seleucid army under Antiochus III in the Battle of Raphia near Gaza. The realization of their military importance leads to demands by native Egyptians for greater privileges and so to the development of racial difficulties which will weaken the Ptolemy dynasty in the future.
Although holding the initiative after the Battle of Raphia, Ptolemy IV, on his chief minister Sosibius' advice, negotiates a peace, and the Seleucid army withdraws from Coele Syria. Antiochus III gives up all his conquests except the city ofSeleucia-in-Pieria.
Greece
Philip V of Macedon, continuing his war with the Aetolian League lays siege to Phthiotic Thebes, captures it and sells the inhabitants into slavery.
Learning of Hannibal's victory over the Romans at Lake Trasimene and seeing a chance to recover his Illyrian kingdom from the Romans, Demetrius of Pharos immediately advises Philip V to make peace with the Aetolians, and turn his attentions toward Illyria and Italy. Philip, at once begins negotiations with the Aetolians. At a conference on the coast near Naupactus, Philip meets the Aetolian leaders and a peace treaty is concluded, ending the three-year-long "Social War".