Leaders ALWAYS lead from the front.
I've heard that maxim loud and clear since before I even took business classes in college. It seems to be the guiding mantra for every hard-headed, and narrow-mind-developing "leader" (read: manager) in almost every school or workplace I've been in. I, in my usual contrarian "I doubt it" mind, have come to really believe it's not "all that".
Leaders can and should lead from the front first, then the rear, and finally from the side.
Leading from the front is the classic lead-by-example, show-the-way, idea which I totally agree with in most cases. In an environment with rules or procedures, this is critical to ensure consistent actions among a team and to carry a culture. It's taking on the hard jobs and doing the same jobs as people several layers down in an organization when necessary. A leader's role is also to create and share a vision, and this has to be done up front and on stage.
But what happens when leaders below you start to emerge and get their own following? THIS is good and it's time to step to the rear, and let these new leaders lead the pack, much like a dogsledding team. The lead dog may be in front and has gained the respect of the other dogs, but the real leader is in the rear, giving helpful guidance to following a path that they may see a bit clearer. Leading from the rear has you step out of the limelight, let others take credit for things you may have started, and let others develop.
And leading from the side? The best quote I heard was about "cheering from the sidelines", where you take a more hands off approach to leading but promote the heck out of a team and coach it's newly developed leaders. Promoting others and their strengths and accomplishments IS a form of leadership, and it's done as a coach cheering from the sidelines. Coaching is a very special type of leadership, and not all leaders can coach. It is really about helping others find their own strengths and use them to their advantage.