Exhibit 31.1

CERTIFICATION UNDER EXCHANGE ACT
RULE 13a-15ANDSECTION 302 OF THE
SARBANES-OXLEY ACT OF 2002

I, Robert F. Baronner, Jr., Chief
Executive Officer, certify that:

1.I have reviewed this annual report on
Form 10-K of Potomac Bancshares, Inc.;

2.Based on my knowledge, this report does not contain any untrue statement
of a material fact or omit to state a material fact necessary to make the
statements made, in light of the circumstances under which such statements were
made, not misleading with respect to the period covered by this annual report;

3.Based on my knowledge, the financial statements, and other financial
information included in this report, fairly present in all material respects the
financial condition, results of operations and cash flows of the registrant as
of, and for, the periods presented in this report;

4.The
registrants other certifying officer and I are responsible for establishing and
maintaining disclosure controls and procedures (as defined in Exchange Act Rules
13a-15(e) and 15d-15(e)) and internal control over financial reporting as
defined in Exchange Act Rules 13(d)-15(f) and 15a-15(f) for the registrant and
have:

a)Designed such disclosure controls and procedures, or caused such
disclosure controls and procedures to be designed under our supervision, to
ensure that material information relating to the registrant, including its
consolidated subsidiaries, is made known to us by others within those entities,
particularly during the period in which this report is being
prepared;

b)Designed such internal control over financial reporting or cause such
internal control over financial reporting to be designed under our supervision,
to provide reasonable assurance regarding the reliability of financial reporting
and the preparation of financial statements for internal purposes in accordance
with generally accepted accounting principles;

c)Evaluated the effectiveness of the registrants disclosure controls and
procedures and presented in this report our conclusions about the effectiveness
of the disclosure controls and procedures, as of the end of the period covered
by this report based on such evaluation; and

d)Disclosed in this report any change in the registrants internal control
over financial reporting that occurred during the registrants most recent
fiscal quarter (the registrants fourth fiscal quarter in the case of an annual
report) that has materially affected, or is reasonably likely to materially
affect, the registrants internal control over financial reporting; and

5.The
registrants other certifying officer and I have disclosed, based on our most
recent evaluation of internal control over financial reporting, to the
registrants auditors and the audit committee of registrants board of directors
(or persons performing the equivalent functions):

a)All significant deficiencies and material weaknesses in the design or
operation of internal control over financial reporting which are reasonably
likely to adversely affect the registrants ability to record, process,
summarize and report financial information; and

b)Any fraud, whether or not material, that involves management or other
employees who have a significant role in the registrants internal control over
financial reporting.

|Date | March 31, 2009 |                         |  | /s/ Robert F. Baronner, Jr. | 
|---- | -------------- | ----------------------- |  | --------------------------- | 
|     |                | Robert F. Baronner, Jr.
|     |                | Chief Executive Officer

A signed original of this written
statement required by Section 302 of the Sarbanes-Oxley Act of 2002 has been
provided to Potomac Bancshares, Inc. and will be retained and furnished to the
Securities and Exchange Commission or its staff upon request.

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