In 1955, Endurance physicist Reginald James wrote a letter full of fascinating insights on Shackleton's leadership to Margery Fisher...
I think he was preeminent as a leader, especially when things were going badly. He had a wonderful power of inspiring confidence and an uncanny flair for the right thing to do. He kept his plans elastic and did not hesitate to change them completely with changing circum-stances. We did not always think his judgement right at the time, but it always turned out to be so. I do not think there is any doubt that we all owe our lives to his leadership and his power of making a loyal & coherent party out of rather diverse elements.