There are many different stories to explain Egypt's invasion of Sumeria. Some say that the Pharaoh Khufu, feeling inadequate compared to the geometric awesomeness of his father's tomb, had chosen to forge a legacy in bloodied bronze and broken ruins in the Levant, and make a name for himself that could only be matched by one of his heirs through building a giant tower shaped like a Penis, or something.
Others say that the High Priest of Thebes was told by Amon that the Nile would not inundate unless it was watered with the blood of Sumerian soldiers. Others say the Patron God of Thebes had communicated that he was sickened with the peacefulness of the Egyptian culture, or maybe just disappointed that the world in general didn't want to fight.
The second theory is the more interesting, as it indicates the growing strength of the Theban Triad, particularly in its head god Amon, revered as the God of Creation, in what is usually considered the golden age of Horus and Egyptian Polytheism. While the High Priests didn't have the control over the Pharaoh that they would wield in the later days of the First Kingdom, they apparently wielded influence significant enough to drastically affect the King's opinion of Sumer.
It also has to be understood that pre-war Egypt was reaching the end of a commercial boom, one that ended, odd enough, with the passing on of Bronze technology from Sumer. As Sumerian merchants competed with the Egyptians in the Mediterranean, the growing merchant class regarded them as the prime cause of the stagnation, an opinion that soon spread upwards and downwards into other levels of society. Sumer's strategic position, threatening the most prosperous parts of the Kingdom in Anatolia and with only the Sinai seperating it from Egypt, made a hypothetical war against Sumer one of the army's greatest nightmares.
The exact cause of the war has been lost to history, but the circumstances could not have been better. With the conflict against the Rus in the north, Sumer had no forces available to defend, while Egypt's army was recently armed with Bronze, and had not yet begun to decline from the wars with the Hittites. This gave Egypt a smashing position at the beginning, but in an extended grapple with Sumer it remained to be seen if they could hold their gains...
Kingdom of Egypt / Shadowbound
Theocratic Monarchy
Age:Bronze
Color: Pink
Economy:Growing 4/1(-1 upkeep)
Army:4(Bronze age)
Navy:2(Bronze age)
Sciences:0
Culture:1
Wonders

yramids(+culture)[Completed]