Who was the first Union general to realize the significance of Cemetery Hill during the battle of Gettysburg (1863) as a defensive position: Buford, Reynolds, Howard, or Hancock? They each claim to be that general.
Howard has priority - he was the commander on the field after Reynolds was dead and before Hancock. He, unlike the others, actually occupied the hill with troops, keeping first a division and later a brigade there while the fighting was taking place on the north.
That said, like many of these "choose the field" controversies, it doesn't take much genius to see that that fishhook position was a good one from attacks coming from the north and west, where the Rebels were. These things were fought out in the 1880s more than they deserved. No need to bring them up now.