General David Petraeus, the top American commander for Iraq and Afghanistan, speaks at Harvard’s Kennedy School of Government at 4 p.m. today. His talk -- which can be viewed on a live webcast here -- is part of a tribute to the more than 300 veterans now studying at Harvard. The U.S. Central Command commander and Army Colonel H.R. McMaster are the two American soldiers most often publicly credited with the rethinking of strategy and tactics that has helped lead to the turn-around in Iraq. So Petraeus’s talk this afternoon -- which Harvard bills as “a conversation on current affairs and leadership with David Gergen, director of the Kennedy School’s Center for Public Leadership” -- may offer a window into where we’ve been and where we’re going as the Obama Administration shifts the American military’s focus more toward Afghanistan.Pictured: Petraeus (center) speaks with an Iraqi Army general while touring the market in Abu Ghraib, Iraq, last August. Photo by U.S. Army Spc. Charles W. Gill.