Johannesburg - An official memorial service will be held for the late struggle stalwart Ahmed Kathrada, the Presidency said on Tuesday."The president has instructed that the national flag fly at half-mast at every station in the country from today, 28 March until the evening of the official memorial service," it said in a statement.Kathrada died on Tuesday morning.President Jacob Zuma sent his condolences to Kathrada's wife, former minister of public enterprises Barbara Hogan; the Kathrada family, and the ANC, "which Uncle Kathy served selflessly throughout his adult life"."The family has requested a private funeral ceremony and the details will be announced by the Ahmed Kathrada Foundation," the Presidency said."An official memorial service will be organised and the details will be announced in due course. Deputy President Cyril Ramaphosa will lead the send-off of the much-loved stalwart within government."Open letter to ZumaLast year, Kathrada wrote an open letter to Zuma asking him to resign."I have always maintained a position of not speaking out publicly about any differences I may harbour against my leaders and my organisation, the ANC. I would only have done so when I thought that some important organisational matters compel me to raise my concerns," he wrote. "Today I have decided to break with that tradition."Kathrada said he did not speak out about the controversy over the upgrades to Zuma's Nkandla homestead, although he thought it wrong to have spent public money for any president’s private comfort.“I did not speak out though I felt it grossly insulting when my president is called a ‘thief’ or a ‘rapist’; or when he is accused of being ‘under the influence of the Guptas’.”He believed the ANC's national executive committee would have dealt with all of that. When he learnt of the dismissal of Nhlanhla Nene as finance minister and the speculated reasons for it, he became very worried. He said he was aware that appointing and dismissing ministers was the president’s prerogative, "This might be technically correct but in my view it is against the best traditions of our movement."Crisis of confidenceOn Monday, the rand dropped against the US dollar after Zuma recalled Finance Minister Pravin Gordhan and his deputy Mcebisi Jonas from an investor roadshow abroad. The move sparked off speculation that Gordhan would be removed from his position in a possible Cabinet reshuffle. In his open letter last year, Kathrada asked Zuma: "Dear Comrade President, don’t you think your continued stay as President will only serve to deepen the crisis of confidence in the government of the country?"And bluntly, if not arrogantly; in the face of such persistently widespread criticism, condemnation and demand, is it asking too much to express the hope that you will choose the correct way that is gaining momentum, to consider stepping down?"If not, comrade president, are you aware that your outstanding contribution to the liberation struggle stands to be severely tarnished if the remainder of your term as president continues to be dogged by crises and a growing public loss of confidence in the ANC and government as a whole."I know that if I were in the President’s shoes, I would step down with immediate effect. I believe that is what would help the country to find its way out of a path that it never imagined it would be on, but one that it must move out of soon."To paraphrase the famous MK slogan of the time, 'There comes a time in the life of every nation when it must chose to submit or fight'. Today I appeal to our President to submit to the will of the people and resign," Kathrada said.