It was an extraordinary sight: Egypt's president addressing the Ethiopian parliament in Addis Ababa over a Nile water dispute that had Egypt openly talking about going to war. But Abdel Fattah Al-Sisi seems to have succeeded where his predecessor failed. His address, punctuated by applause from Ethiopian parliamentarians, came after a deal was reached in Khartoum between Egypt and Ethiopia, with Sudan as the broker, over an agreement of principles that has been years in the making on Ethiopia's Grand Renaissance Dam. The entente was a far cry from the warning issued by former Egyptian president Mohamed Morsi that every drop of water stolen from the Nile would be defended by a drop of Egyptian blood, or from a live Egyptian TV studio debate over the possibility of sending Egyptian warplanes to bomb the dam. Negotiators for both sides had to overcome a distrust that accompanies all water disputes. Ethiopia rightly complains that colonial-era water treaties gave Egypt a virtual monopoly over Nile waters. Egypt believes its “historic rights” to the Nile are guaranteed by treaties from 1929 and 1959 which grant it 87 percent of the river's flow and the power to veto upstream projects. Egypt, heavily dependent for millennia on the Nile for agriculture and drinking water, and in fact its way of life and very existence, feared that the Grand Renaissance Dam would decrease its water supply. That fear did not stop Nile Basin countries, including Ethiopia, from signing another deal in 2010 allowing them to work on river projects without Cairo's agreement. That is when the proverbial dam broke. Neither Sudan nor Egypt signed that deal, after which the warmongering and posturing began. Just as Cairo was concerned the Ethiopian dam would reduce the flow of the Blue Nile, Addis insisted the project was essential for its development and the well-being of a growing population which at 90 million people is not much less than that of Egypt. The biggest obstacle would have come once the dam is completed and the reservoir is filled. A reservoir this huge - it will be Africa's largest when completed in 2017 and will generate 6,000 megawatts of electricity - will hold 63 billion cubic meters — roughly as much water as Egypt gets from the Nile over the course of a year. If the basin were to be filled too fast, Egypt's farmers would plunge into drought and its own hydropower dams would stop producing electricity. The trick was to find the right balance between water coming fast enough to satisfy Ethiopia's grand ambitions but slow enough not to hobble Egypt's economy. What the three countries eventually signed was an outlining of principles by which they will cooperate to use the water fairly. Ethiopian Prime Minister Hailemariam Desalegn confirmed at the signing ceremony that the construction of the dam will not cause any damage to the three states, especially to Egypt, while Al-Sisi said the three had chosen cooperation, and to trust one another for the sake of development. Africa has big aspirations and needs big projects to utilize the vast resources it possesses. Countries can go to war over water which is more precious than territory. In this case, the corollary is that water brought people into a room who wouldn't normally sit in a room together. When it comes to water, even the bitterest rivals eventually end up having to take up arms or negotiate. Two powerful African economies, Egypt and Ethiopia, have moved a step toward the latter.