I am enclosing the famous story of Francis Webster. The interesting thing to note about his story, is the angels seem to have come even before the snow. Not that he talks about making it to a "patch of sand" He was likely referring to the hills of Western Nebraska, before the snows came. The Black Hills area was one of the most difficult of the journey. The article linked at the end from Chad Orton talks about this.
Some years ago president David O. McKay told from this pulpit of the experience of some of those in the Martin handcart company. Many of these early converts had emigrated from Europe and were too poor to buy oxen or horses and a wagon. They were forced by their poverty to pull handcarts containing all of their belongings across the plains by their own brute strength. President McKay relates an occurrence which took place some years after the heroic exodus: “A teacher, conducting a class, said it was unwise ever to attempt, even to permit them [the Martin handcart company] to come across the plains under such conditions.
“[According to a class member,] some sharp criticism of the Church and its leaders was being indulged in for permitting any company of converts to venture across the plains with no more supplies or protection than a handcart caravan afforded.
“An old man in the corner … sat silent and listened as long as he could stand it, then he arose and said things that no person who heard him will ever forget. His face was white with emotion, yet he spoke calmly, deliberately, but with great earnestness and sincerity.
“In substance [he] said, ‘I ask you to stop this criticism. You are discussing a matter you know nothing about. Cold historic facts mean nothing here, for they give no proper interpretation of the questions involved. Mistake to send the Handcart Company out so late in the season? Yes. But I was in that company and my wife was in it and Sister Nellie Unthank whom you have cited was there, too. We suffered beyond anything you can imagine and many died of exposure and starvation, but did you ever hear a survivor of that company utter a word of criticism? Not one of that company ever apostatized or left the Church, because everyone of us came through with the absolute knowledge that God lives for we became acquainted with him in our extremities.
“‘I have pulled my handcart when I was so weak and weary from illness and lack of food that I could hardly put one foot ahead of the other. I have looked ahead and seen a patch of sand or a hill slope and I have said, I can go only that far and there I must give up, for I cannot pull the load through it.’” He continues: “‘I have gone on to that sand and when I reached it, the cart began pushing me. I have looked back many times to see who was pushing my cart, but my eyes saw no one. I knew then that the angels of God were there.
“‘Was I sorry that I chose to come by handcart? No. Neither then nor any minute of my life since. The price we paid to become acquainted with God was a privilege to pay, and I am thankful that I was privileged to come in the Martin Handcart Company.’” (Relief Society Magazine, Jan. 1948, p. 8.)