Bethesda-based EagleBank announced today it has reached an agreement to acquire Alliance Bankshares of Chantilly for about $31.2 million, or $6.11 per share.

The merger will give EagleBank an additional $536 million in assets, $412 million in deposits and six branches in Northern Virginia. Both boards have given a thumbs up on the deal, which is expected to close in the fourth quarter, subject to shareholder and regulatory approval.

EagleBank chairman and chief executive Ronald D. Paul said the bank has yet to determine what role Alliance president and chief executive William E. Doyle Jr. will play in the new entity, or how many Alliance employees will remain.

Once the deal is completed, EagleBank will boast some $3 billion in assets and $2.3 billion in deposits. The bank expects the transaction will boost earnings within 12 months of closing.

Paul has long expressed interest in gaining a stronger foothold in Northern Virginia, where the bank has four branches currently under development. All told EagleBank has 13 branches in the Washington area.

“This is a great opportunity for us to fill out the marketplace and take over a bank that has a huge upside for us,” he said. “The efficiencies are tremendous. They have a wonderful business of title companies, as we currently do. So the opportunity will be huge for us to tie those two together.”

In the second quarter, Alliance Bank reported profits of $365,000, or 7 cents per share, compared to net income of $114,000, or 2 cents per share, for the same period a year earlier.

EagleBank has been growing at a steady clip over the past several quarters most recently recording a 58 percent year-over-year increase in earnings to $4.9 million for the three months ending June. During that time, its loan portfolio grew by 30 percent, or $444 million, for a total book of $1.9 billion.

Earlier this month, Treasury awarded the bank $56.5 million through the Small Business Lending Fund, $23.3 million of which it used to redeem the remaining shares tied to the Troubled Asset Relief Program. At the time of the award, Paul said he anticipated the SBLF injection would help sustain EagleBank’s blossoming loan portfolio.