Today marks the beginning of the week-long ceremonies commemorating the 150th anniversary of the Battle of Gettysburg. There will be a full re-enactment of the battle, discussions with panels of historians, and of course a re-reading of the Gettysburg Address.

But as Lincoln affirmed when he dedicated that hallowed ground, nothing we say or do can “add or detract” from the great sacrifice made there. Gettysburg was a defining moment in the history of our nation; and consequently, one of the most important battles in the history of mankind.

I’ve had the honor of visiting Gettysburg twice, most recently during the One Nation Bus Tour in 2011. I brought my family with me and we met other families—even meeting up with friends traveling from Wasilla—as we paid our respects to the monuments and patriot graves. It was important for me to bring the younger generation there in order to instill in them a sense of the duty we owe to the ordinary men who did extraordinary things to make us one nation.