I just finished a book about three Italians held in a British POW camp during WWII in Kenya, who decided, out of pure boredom, to climb the nearby Mt Kenya (17,200’). They had been prisoners for two years and “In order to break the monotony of [prison] life one had only to start taking risks again..” So they did.
They made their own ice axes, crampons, tent, and sleeping bags from scraps around the camp and saved up food for several weeks. Beside the danger of climbing the mountain – which had only been climbed 5 times before – they had to walk miles through lion, elephant, rhino and buffalo terrain. (On a previous climb of the mountain, a climber had been pulled from his tent by a lion and had his leg chewed off.) They had a close encounter with a bull elephant but weren’t attacked by any animals.
The only information they had on the mountain was from an old magazine article which was smuggled into the camp, and from a label on a can of meat which had a drawing of Mt. Kenya.
After 18 days on the mountain, they reached the lower summit and were turned back by weather and lack of food. Before they escaped, they knew they would have to return to the camp because it was just too far to fully escape captivity. So they sneaked out of camp one night and 18 days later, they sneaked back in. But they were discovered and had to spend 28 days in solitary. And three more years in the prison camp. A flag they left on the summit was found by a later party which validated their story. A Wikipedia version of their story is here.