An invincible hope

Wikipedia tells of the heroic rescue by Ernest Shackleton in 1916. 

Elephant Island is most famous as the desolate refuge of Ernest Shackleton and his crew in 1916. Following the loss of their ship Endurance in Weddell Sea ice, the 28 exhausted men reached Elephant Island after a harrowing ordeal on drifting ice floes. They established a camp at a place they called Point Wild where they were able to regain some strength.

Realizing that there was no chance of rescue, Shackleton decided to sail to South Georgia where he knew there was a whaling station. In one of the most incredible feats in the history of sailing and navigation, Shackleton sailed with five other men on an 800-mile (1,287 km) voyage in the open lifeboat James Caird on Easter Monday, April 24, 1916, arriving at South Georgia almost two weeks later. His second-in-command, Frank Wild, was left in charge of the men on Elephant Island, waiting for Shackleton's return with a rescue ship. In his memoir Wild recalled “We gave them three hearty cheers and watched the boat getting smaller and smaller in the distance. Then seeing some of the party in tears, I immediately set them all to work.”

Many of the crew were already ill and frostbitten, and they were now also in danger of starvation. After four and a half months, one of the men spotted a ship on August 30, 1916. The ship, led by Shackleton, was the borrowed tug Yelcho, from Punta Arenas,Chile, commanded by Luis Pardo, which rescued all the men who had set out on the original expedition. It was the fourth attempt to rescue the men. The first three attempts were turned back due to a heavy ice pack surrounding the island.

In his commentary on the book of Hebrews, chapter 4, J Reed uses this story as an example, noting: 
Christians have a saving and a creative work to do: to reach the lost with the gospel and to make provision for the people of God. Shackleton was motivated to move mountains for his marooned colleagues by three things at least:

(a) Love for his men
(b) A sense of duty. They were his men and he felt an obligation to them
(c) An invincible hope. He never doubted but for a moment that he would bring off the rescue.

I love that line about 'an invincible hope.'