To understand the community banking world is to understand that bankers like to run in packs.

A new guy takes over, and it won’t be long before he starts to bring in folks he’s worked with before. Relations are paramount.

I’ve known this for a while but never quite appreciated it until last week when I was invited to stop by a little get-together in Alexandria hosted by John Marshall Bank.

John Marshall, based in Falls Church, is establishing a small office in the city with the hopes of one day opening a branch. Its foray is led by some bankers who used to work at Burke & Herbert, a longtime Alexandria institution. They left Burke & Herbert after a former Chevy Chase Bank executive arrived to take the reins there and brought along some of his associates.

The Chevy Chase crew, in turn, had left their employer after it was bought by Capital One.

John R. Maxwell, the chairman and chief executive at John Marshall, has had plenty of experience with this sort of serial banking. He came to Northern Virginia from Colorado in 1988 to work with a bank in Arlington, and eventually came to run James Monroe Bank. James Monroe was bought by Mercantile Bank at a hefty premium in 2006, which itself was then bought by PNC a short time later.

Maxwell, suffice it to say, did very well for himself and his investors, getting out before the financial market meltdown.

In early 2008, he engineered the takeover of Security One Bank, an institution that had been catering to a Hispanic clientele, but which had been hurt by the downturn.

The bank renamed itself John Marshall and began pursuing small businesses and a broader customer base. Last year, it turned its first profit and assets have grown from $62.7 million at the end of March 2008 to $309.9 million by the end of 2010. It successfully raised $22 million in 2008 and is on its way to wrapping up another $10 million round now.

The bank has signed a lease to move its headquarters to Reston later this year and is eyeing potential acquisitions.

Bankers move in packs, but Maxwell seems one step ahead.