Lt Gen Pecos Kutesa, a former army representative in parliament, is dead.
He was 65.
UPDF spokesperson Brig. Flavia Byekwaso said he had been hospitalized in India but did not share details of his illness.
"UPDF fraternity regrets to announce the passing on of Lt Gen Pecos Kutesa which occurred today in India," the defense spokesperson tweeted today evening, promising more details.
Gen. Kutesa, who was among the UPDF chiefs that were recently retired from the force, participated in the bush war the brought the current government to power.
He served the UPDF in different capacities and detailed some of his achievements in his biography titled "Uganda's Revolution 1979-1986: How I Saw It".
Lt. Gen. Pecos Kutesa was one of Museveni's first bodyguards during the war and he is among the first twenty-six people to join the guerilla war that brought NRA, now NRM, to power.
Agriculture Minister Frank Tumwebaze said it was "sad" losing the general, adding: "what a great & deep brain!!!"
"Condolences to his dear wife, family, relatives & the [UPDF]," he posted on Twitter.
Century Books Library Uganda Books described him as "a very good writer", and wished his soul to "rest in peace."
Elison Karuhanga, a partner at Kampala Associated Advocates, wrote on Twitter: "Deepest condolences to the family of this hero... a general of the resistance."
Ivan Ojakol, also a lawyer, tweeted: "Eternal repose to his soul! He wrote a brilliant book, 'Uganda's Revolution 1979-1986: How I saw it' perhaps the most honest account of the NRM war."