General Sir Richard Dannatt, who has visited the southern African country several times in recent years, said the British Army had established a staff college in Harare after 1979 "to underpin the professional development of post-UDI army".
The former British colony of Southern Rhodesia made its Unilateral Declaration of Independence (UDI) in 1965 under white rule and did not achieve majority African rule, under the new name of Zimbabwe, until 1979.
Lord Dannatt told the House of Lords: "I often reflect now that there must be a generation of Zimbabwean army officers out there, who were trained by us in the 1980s, who know that there is a better way than that of the repressive dictatorship of Robert Mugabe."
The crossbench peer, in his first Lords speech since being appointed by Prime Minister David Cameron last year, went on: "Will they, I wonder, ever find the moral courage to stand up and do the right thing? They know what that is. We taught them."
Lord Dannatt, who was tipped by Cameron before the general election as a future Tory minister, was speaking in a Lords debate on Zimbabwe, opened by Liberal Democrat ex-MP Lord Avebury.
The strife-torn country is ruled, in an uneasy power-sharing deal, by Mugabe’s Zanu PF party and two rival factions of the Movement for Democratic Change (MDC). Another election is due this year, with no agreement on when it should happen.
Foreign Office minister Tory Lord Howell of Guildford, replying to the debate, told Lord Dannatt: "We listened with great interest to what you had to say."