It has become common knowledge that Cyrus H. McCormick invented and manufactured the mechanical reaper, but it was actually his father’s genius as a simple inventor that led to the family’s riches and renown.
According to research compiled by Norbert Lyons, Cyrus’ mother Polly encouraged her husband Robert to give Cyrus his inventions as a gift and allow Cyrus, the assertive and most business minded member of the family, to make the most of it. According to multiple accounts from family members and close friends, Robert had already invented the reaper after years of working on it, ran initial test trials in 1831, and gave it to his son Cyrus as a gift. Cyrus patented his first version of the reaper in 1834.
Here’s Norbert Lyons’ telling of how the gift transaction from parents to son occurred:
“Without her beloved son Cyrus at her side, Polly McCormick knew the declining years of her life would be empty and dreary. She must manage, somehow or other, to keep Cyrus at home.
“An idea occurred to her. If she could induce her husband to give Cyrus an invention or two, particularly the one in which the whole family had the greatest faith and confidence—the reaper—that might deter him from straying far afield in order to find a fitting instrument to realizing his life’s ambition. If he could make a success of the machine, if he could cause the farmers of the country to use it, the Walnut Grove [VA] shops could not begin to meet the demand. The plant would have to be enlarged, and the young promoter might conceivably see his dreams of fame and fabulous wealth come true without leaving the homestead.
“That the idea would appeal to Cyrus she felt certain, but she was not so sure that Robert would readily accede to it. He would have to be less than human to cede to his son, without a struggle, his rights and interests in the invention on which he had expended his brain and muscle for a whole generation, and which only now  was beginning to show some promise of success. However, Polly had never before failed to carry a point with her husband, and she felt confident that in the end, she would be no less successful this time, although she realized that on no previous occasion had she called upon him to make a personal sacrifice of such magnitude and importance. From the family reminiscences and records available, we can reconstruct the sequence of events from her on with reasonable plausibility.
“Robert, of course, remonstrated against his wife’s proposal. He was willing to do anything within reason for his children, especially for Cyrus, now that the boy was about to attain his majority, but, he pleaded, wasn’t this a rather unusual and unreasonable request? If the reaper or any other of his [Robert’s] inventions had a substantial, permanent value, if they were destined to produce a fortune, were not the other children also entitled to profit by their success?
“But Polly was not to be turned aside so easily. Of course, she agreed, the other children should also profit by his inventions, but Cyrus would be glad to make that a binding condition of such a gift. She had sounded him out on the subject and he had promised that if he ever made a success of any of the machines he would share his good fortune with his brothers and sisters. Thus Robert’s principle argument was confuted.
“Still Robert objected. Somehow the abdication of his rights to his children, in his own brain, went against his grain. It did not seem to him the right thing to do; he had never heard of anyone doing such a thing. Against these scruples Polly also had a ready argument. Surely, she told him, his inventions were his own property, just as were his house, land and personal effects. He could do with them as he pleased, dispose of them in any manner he saw fit.
“As for the personal honors that might result from the successful exploitation of the machines, he should be willing to forego them in favor of his oldest son. He was getting along in years, soon he would be fifty; the best part of their lives was behind them; they had little to look forward to except the happiness and welfare of their children.
“And now that Cyrus was about to reach man’s estate he must prepare himself to assume the family leadership when Robert and she were gone. She, personally, was ready to give him every possible aid and comfort, as Robert was, of course, and if any honors or personal distinction should ever attach to the reaper invention, she was perfectly willing that Cyrus should have it, especially if it would advance the commercial success of the machine and thus benefit the whole family.
“It was a sacrifice Robert could well afford to make, she insisted. The whole future welfare and happiness of the family might depend upon it. And if Cyrus did make a success of the machine, what a splendid legacy it would be for the boy, one in which the other children would also share!
“In the end, as might have been expected, Robert capitulated to the arguments and importunities of his stronger willed wife. Thus it came about that on an indeterminate date Robert McCormick made a present of his reaper invention to his oldest son Cyrus. It was not a formal grant or transfer, ratified by a duly recorded legal instrument, but a purely informal procedure actuated solely by the family motives to provide Cyrus with a congenial occupation that would keep him from straying from the Walnut Grove fireside and create a potentially valuable heritage for all of Robert and Polly McCormick’s children.”
In 1885, the year after Cyrus’s death, Cyrus’ brother Leander and Cyrus McCormick Jr. collected sworn statements and accounts from family members, friends and old neighbors, all claiming that Robert H. McCormick had given the already invented reaper to his son Cyrus. In 1910, Robert Hall McCormick (Leander’s son) and James Hall Shields (Leander’s nephew) republished Leander’s collected statements along with additional testimonies and a brief biography of their grandfather, Robert H. McCormick.
In the end, the publicity behind the name Cyrus McCormick was more than Leander’s efforts could overcome, but the documentation for a different story was quite complete. Beyond the collection of statements that Leander produced and letters written by neighbors of the time, the only account of Robert McCormick as inventor of the reaper is found in Norbert Lyons’ The McCormick Reaper Legend, published in 1955 in cooperation with the McCormick family.
Sources: The McCormick reaper legend; the true story of a great invention, by Norbert Lyons, New York : Exposition Press, [c1955] online at http://catalog.hathitrust.org/Record/006293956