The young royal, who just turned six-months-old, was smiley and wriggly as he accompanied his parents on their 10-day tour of Southern Africa earlier this year.
"I tell you what, [Archie] clearly loves Africa as well, because he was up looking out the window, he's found his voice now," Harry told locals in Cape Town.
"He was bouncing up and down, he's making more noise than he's ever made, and he's smiling all the time."
While Harry enjoyed travelling around Africa with his son, he said he was in awe of military families who were often required to spend months and years apart.
"It's unbelievably hard. I have so much respect and admiration for anyone who has to deal with that," he said.
One mum, whose husband is attached to the Welsh Guards, told The Sun she had enjoyed swapping stories with Meghan.
"My daughter Aeris is the same age as Archie and we talked about weaning and the children beginning to crawl – she's just a normal mum and it was like talking to a friend," Amy Thompson said.
The visit comes ahead of Remembrance Sunday, when the United Kingdom will pay tribute to all service members who have lost their lives in military conflicts since World War I.
"Every year during the month of November we pause to remember and honour all those who have served their country here in the UK, across the Commonwealth and around the world," the royal family said.
But Harry and Meghan also wanted to show support for the families of service personnel who are currently deployed overseas, it said.
"A reminder that a life of service does not simply describe the person wearing the uniform, but the entire family," a statement said.
Later on Thursday, the Duke and Duchess of Sussex attended a sombre service for fallen heroes at Westminster Abbey's Field of Remembrance.
The couple laid poppies and two crosses as a bugler played the Last Post.
The Duke and Duchess of Sussex attend a sombre service for fallen heroes at Westminster Abbey's Field of Remembrance. Photo / Getty Images
The Duchess of Cornwall was supposed to accompany the couple at the ceremony, but had to cancel due to falling ill.
"The Duchess of Cornwall has been told by her doctor to cancel her engagements owing to a chest infection which has got progressively worse over the last few days," a spokesman for Clarence House said.
