Artaxerxes I (r.464-425 BC) was the Persian Emperor during the last stage of the Greco-Persian War and the first part of the Great Peloponnesian War, ending the first of those wars with the Peace of Callias, in which the Athenians acknowledged Persian authority in Asia Minor. The Greeks called him Artaxerxes Macrocheir (Long hand)
Artaxerxes came to the throne after the assassination of Xerxes I in 464. Xerxes was assassinated by his minister Artabanus. There are two versions of these events. In the first Artabanus killed Xerxes' son Darius, and then killed the Emperor to avoid his revenge. In the second he killed Xerxes, and then convinced his other son Artaxerxes that Darius had done the deed. Artaxerxes then killed his brother, and took the throne as Artaxerxes I. Artabanus remained the power behind the throne for seven months, but was then betrayed by Megabyzus, one of his fellow conspirators, and was killed in single combat by Artaxerxes.
Artaxerxes faced a number of revolts within his empire. The first was led by another surviving brother, Hystaspes, satrap of Bactria in the far east of the Empire.
Artaxerxes inherited the ongoing Greco-Persian War, largely being fought in Asia Minor after the failure of Xerxes's invasion of Greece in 480-479. The Greeks had formed the Delian League, led by Athens, to conduct the war. In 466 a Persian fleet had been destroyed by the Delian League (battle of the Eurymedon River), removing the direct Persian threat to the Aegean.
460 saw the start of the First Peloponnesian War, a series of clashes between Athens, Sparta and their allies. The Persians didn’t intervene directly in this war, but they did use their gold (the famous 'Persian Archers', named after the image of an archer on one side of their coins) to influence the war. At this stage they tended to support the Athenians against Sparta.
In 460 or 459 Egypt revolted against Persian rule under the leadership of Inaros. Artaxerxes sent an army under his brother Achaemenes, but this army was defeated and Achaemenes was killed at the battle of Pampremis. The survivors of this army ended up under siege at the 'White Castle' near Memphis. The Delian League sent an army to Egypt to support Inaros, but almost the entire force was lost when Artaxerxes sent a second invasion force (c.454 BC). The Persian counterattack was led by Megabyzus, now satrap of Syria. Inaros was eventually forced to surrender, and was later killed despite having been promised his safety by Megabyzus, who briefly rebelled against Artaxerxes in the aftermath
The Greco-Persian War ended in 448 when Artaxerxes and the League agreed the Peace of Callias, possibly triggered by a Greek victory at Salamis of Cyprus (450 BC). The peace effectively acknowledged the status quo, with the Persians agreeing to keep out of the Aegean and the League acknowledging their rule in Asia Minor. Two years later the First Peloponnesian War also ended, with the 'Thirty Years Peace'.
The Athenians kept to the Peace of Callias until 439, when they attacked Samos. This triggered a period of conflict with the Persians that saw them achieve some successes.
Artaxerxes I was still on the Persian throne when the Great Peloponnesian War broke out in 431, but the Persians played little part in this first stage of the war. Artaxerxes died in 425 and was succeeded by his son Xerxes II, who ruled for only 45 days before being murdered. He was succeeded by Darius II, who was Emperor for the second part of the Great Peloponnesian War.