During his long tenure in the midst of the surrounding political chaos of the Greek Dark Ages, Egypt was beset by foreign invaders (including the so-called Sea Peoples and the Libyans) and experienced the beginnings of increasing economic difficulties and internal strife which would eventually lead to the collapse of the Twentieth Dynasty. In Year 8 of his reign, the Sea Peoples invaded Egypt by land and sea. Although Ramesses III defeated them in 2 great land and sea battles, he was unable to stop the creation of several new states by these people in parts of the Asiatic Egyptian Empire. The heavy cost of these battles slowly exhausted Egypt's treasury and contributed to the gradual decline of the Egyptian Empire in Asia. The severity of these difficulties is stressed by the fact that the first labor strike in recorded history occurred during Year 29 of Ramesses' reign, when the food rations for the favoured royal tomb-builders in the village of Set Maat her imenty Waset (now known as Deir el Medina), could not be provisioned. The reason for this deficiency was due to the the 1159 BC eruption of the Hekla III volcano in Iceland, which expelled up to 12 cubic kilometres of rock into the atmosphere and caused large-scale failures of the crop harvest. The presence of significant quantities of volcanic soot in the air prevented sunlight from reaching the ground and also arrested global tree growth for almost two full decades until 1140 BC. The result in Egypt was inflationary grain prices; however, the prices of fowl remained stable during this difficult period.

These realities are completely ignored by the images of continuity and stability presented in Ramesses' official monuments – most of which seek to emulate his more famous predecessor, Ramesses II. He built important additions to the temples at Luxor and Karnak, and his funerary temple and administrative complex at Medinet-Habu is amongst the largest and best preserved in Egypt – however the uncertainty of Ramesses' times is apparent from the massive fortifications which were built to enclose the latter. No Egyptian temple in the heart of Egypt prior to Ramesses' reign had ever needed to be protected in such a manner.