but the lessons remain relevant for today's military as we learned today in fort leavenworth.ravery and sacrifice of d-day. >> it was one of the most complex operations in history at that time. there was a naval component. there was an air component. there was airborne component. there was a deception operation. all of these things kind of come together to make d-day. >> reporter: fighting the germans was only a small piece of the puzzle. >> the rate at which we needed to put individuals from england across the channel onto the coast required immense effort, more than even the fighting that is going to be taking place. >> reporter: years of planning went into getting enough soldiers into france and food and weapons to beat back the nazi forces. even the weather had to be just right. >> it's a human problem, logistics, firepower, how do you apply all these at the exact time and place to get the desired effects. >> reporter: students watched a lure hour-long presentation. eisenhower oversaw the d-day invasion. >> if they had not succeeded at d-day, the outcome is almost unfathom