Merenptah was the thirteenth son of Pharaoh Ramesses II. and his mother was queen Isetnofret. He ruled together with his father from 10 to 12 years (as a general of his soldieries at the beginning) and after his death Merenptah continued in initiated work of his father. According to Manetho Merenptah ruled for 19 years and 6 months and this is right, if we took the reign together with his father into consideration.
The biggest success during the reign of Merenptah was repulsing the incursions of Libyans and sea nations in the 5th year of his reign. He likely led the winning campaign into Asia, which proves the "Israel Stele", the only preserved document in the western Asia.
Merenptah focused the construction activity especially in the area of west Thebes (Waset) and Memphis (Mennefer). He built only one funereal sanctuary from a block of ruined Amenhotep III sanctuary and a complex of palace sanctuary in honour of Ptah and the royal cult.
Merenptah kept a peace agreement with the Hittites - on the basis of it he helped the Hittites at the time of great famine. He moved with the royal court back to Memphis (Mennefer). The Jews' exodus out of Egypt dated to the time of his reign.
Also many literary works came from the time of Merenptah's reign, e.g. "The legend about two brothers". Merenptah was buried in the tomb KV 8 in the Valley of the Kings. His mummy was found in a hideaway of mummies in the tomb of Amenhotep II – so in tomb KV 35.