After the historic victory on April 30, 1975, which liberated the South and reunified the country, the whole Vietnam embarked on a new mission — promoting peace and reconstructing the nation with century-defining projects. On the fierce Da River, over 30,000 engineers, sappers, and construction workers battled against rocky mountains and raging floods to achieve a remarkable feat. The Hoa Binh Hydropower Plant, the largest of its kind in Southeast Asia at that time, officially began generating electricity, lighting up the North and ushering in a new era of industrialisation.