Herodotus states that Psamtik had ruled Egypt for only six months before he was confronted by a Persian invasion of his country led by King Cambyses II of Persia.

He succeeded his father as pharaoh in 526 BC, when Amasis died after a long and prosperous reign of some 44 years.

A few days after his coronation, rain fell at Thebes, which was a rare event that frightened some Egyptians, who interpreted this as a bad omen.

After the Persians, under Cambyses, had crossed the Sinai desert with the aid of the Arabians, a battle was fought near Pelusium, a city on Egypt's eastern frontier, in the spring of 525 BC[2] and the Egyptians were defeated.

Shortly thereafter, Cambyses ordered the public execution of two thousand of the principal citizens, including (according to some sources) a son of the fallen pharaoh.