After outfoxing Egypt on the diplomatic stage for more than a decade, Ethiopia is set to officially inaugurate one of the world's biggest dams on a tributary of the River Nile, burying a colonial-era treaty that saw the UK guarantee the North African nation the lion's share of its water.
The dam - built on the Blue Nile at a cost of about $5bn (£3.7bn), with a reservoir roughly the size of Greater London - has led to a surge in Ethiopian nationalism, uniting a nation often polarised along ethnic lines and mired in conflict.
Ethiopians may disagree on how to eat injera [their staple food], but they agree on the dam, Moses Chrispus Okello, an analyst with the South Africa-based Institute for Security Studies think-tank, told the BBC.
They do not see it as a pile of concrete in the middle of a river, but as a monument of their achievement because Ethiopians, both at home and in the diaspora, funded the dam's construction. There were waves and waves of appeals for contributions when construction started in 2011.
Named the Grand Ethiopian Renaissance Dam (GERD), it is Africa's largest hydro-electric plant, raising hopes that not only will it meet the 135 million-strong population's energy needs but it will also give the country energy hegemony and boost its foreign currency earnings.
Ethiopia was planning to increase the sale of electricity to neighbouring countries such as Kenya and Djibouti, with ambitions of building a transmission network to cross the Red Sea to sell to Middle Eastern states like Saudi Arabia, he said.
But for Egypt, the dam represents the opposite of Ethiopia's hopes and ambitions. It fears that dam could sharply reduce the flow of water to the country, causing water shortages.
About 93% of Egypt is desert, with almost no people. All of us, 107 million people, live on the Nile, a geologist at Egypt's Cairo University, Prof Abbas Sharaky, told the BBC.
Prof Sharaky said that despite the Blue Nile being an international river, Ethiopia took a unilateral decision to build the dam - something it succeeded in doing only because Egypt was hit by a revolution at the time, leading to the overthrow of long-serving ruler Hosni Mubarak.
Ahead of the GERD's inauguration on Tuesday, Egypt's Foreign Minister Badr Abdelatty stepped up his government's rhetoric against the dam, saying that water security was a red line and the dam posed an existential threat to the North African state.
However, Prof Sharaky ruled out the possibility of Egypt going to war with Ethiopia. They are our brothers. We drink from the same water. The Nile is coming from them, he said.
Ethiopia has previously stated that studies showed Egypt's concerns are unfounded, and the dam is far from areas prone to earthquakes.
So Ethiopians are unlikely to let Egypt dampen their mood as they prepare to celebrate the dam's inauguration and focus on their next goal - to regain access to the Red Sea, which Ethiopia lost when Eritrea gained independence in 1991.
The issue of a seaport is no longer something to be ashamed of. The global perspective is clear - there is no large country without port access, and this should be approached through negotiation, Prime Minister Abiy added.