In order to make PC's effective leaders, your PCs must demonstrate their ability to lead. Only then will they draw attention and inspire people to follow them.
Here's a fun idea. Put them in the political arena... as waste management officers.
Concept: The nobility of your city are renowned for being petty and outlandish, having entirely too much money and free time on their hands. Nobles have a "rags to riches" contest, each one pulling up a "commoner" (ie. the PC's) to transform into a member of the nobility with promises of power and fortune.
The joke is, the PC's are promised a seat on the council. What they are NOT told, is they are made the heads of all the menial and undesirable trades of the city; garbage collection, corpse retrieval, stable cleaner, whatever the nobles can come up with.
I'm not 100% sure how this would play out, but really try to accentuate how "common" the PC's are. I see some sort of labour union forming out of this scenario; they form their own "guild" of commoners who look up to them and, as war arises, become willing to assist them in whatever capacity they can. The labour union becomes a unit of irregulars and, under the leadership of the PC's, somehow save the day... this, in turn, gets them the attention of the local ruler who, after learning how stupid his nobles have been, offers the PCs some new titles, which grants them leadership over ACTUAL military units...
Thoughts?