Festus Mogae, who led Botswana through a decade of democratic stability and a nationally transformative fight against HIV/AIDS, died on Friday at the age of 86, the government announced. No cause of death was immediately released.

Mogae, an economist by training who served as governor of the Bank of Botswana before his presidency, was sworn in as the country’s third president in 1998 and served two terms, handing over power peacefully in 2008. His presidency was defined by an urgent public health response: at the time he took office, Botswana had one of the highest HIV/AIDS prevalence rates in the world. In 2002, Mogae’s government launched free access to antiretroviral drugs at public health facilities, a pioneering move in sub-Saharan Africa that was later extended to noncitizens. The policy was credited with a sharp decline in the disease’s prevalence.

In an address to the nation, President Duma Boko declared three days of national mourning, calling Mogae “a distinguished statesman, a patriot whose life was devoted to the service of his country.” Boko said Mogae carried the name of Botswana with dignity across the world and remained a voice of reason, unity and progress throughout his life.

Mogae’s democratic leadership earned international recognition: in 2008 he received the Ibrahim Prize for Achievement in African Leadership, a $5 million award granted to former African heads of state who demonstrate excellence in governance, respect for constitutional limits, and a peaceful transfer of power. Botswana, a sparsely populated and arid country in southern Africa, is the world’s largest diamond producer by value, with diamonds accounting for around 80% of exports and a quarter of gross domestic product, according to the International Monetary Fund. Mogae, an economist by profession, was credited with sound economic management that maintained stability during his tenure.