<PAGE>   1
================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                              Washington, DC 20549


                                   FORM 10-Q/A


                QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d)
                     OF THE SECURITIES EXCHANGE ACT OF 1934


For the quarter ended June 30, 1998                Commission File Number 1-9897


                            VALLEY FORGE CORPORATION
                            ------------------------
             (Exact name of Registrant as specified in its charter)


        DELAWARE                                         58-0833796
        --------                                         ----------
(State of incorporation)                    (IRS Employer Identification Number)


       100 Smith Ranch Road, Suite 326, San Rafael, California 94903-1994
       ------------------------------------------------------------------
               (Address of principal executive offices) (Zip code)


                                 (415) 492-1500
                                 --------------
              (Registrant's telephone number, including area code)



Indicate by a check mark whether the Registrant (1) has filed all reports
required to be filed by Section 13 or 15(d) of the Securities Exchange Act of
1934 during the preceding 12 months (or for such shorter period that the
Registrant was required to file such reports) and (2) has been subject to such
filing requirements for the past 90 days.  YES [X]   NO [ ]

The number of shares outstanding of Registrant's Common Stock, par value $.50
per share, at August 10, 1998, was 4,132,089.

================================================================================


<PAGE>   2

                    VALLEY FORGE CORPORATION AND SUBSIDIARIES


Item 4.  Submission of Matters to a Vote of Security Holders

(a)    The Company's Annual Meeting of Shareholders was held on June 10, 1998.
       Represented at the Meeting, either in person or by proxy, were
       3,821,061 voting shares, of a total below.

(c)    (i)    To elect five directors to serve for one-year terms or until
              their successors are elected and qualified. All nominees are
              named below.



               NAME OF DIRECTOR       VOTES FOR ELECTION         VOTES WITHHELD

               Martin J. Bloom            3,820,367                    694

               David R. Brining           3,820,567                    494

               Theodore P. Desloge        3,820,567                    494

               Phillip F. Dressel         3,820,567                    494

               Dale J. Warner             3,820,567                    494

       (ii)   To ratify the Board of Directors' appointment of Deloitte &
              Touche LLP as auditors for the Company for 1998.

              Votes for Proposal         3,811,777
              Votes Against Proposal         8,802
              Votes Abstaining                 482

       (iii)  To approve the adoption of an amendment to the Company's
              Certificate of Incorporation to increase the number of shares
              of common stock from 5,000,000 to 10,000,000 shares.

              Votes for Proposal         3,784,055
              Votes Against Proposal        34,716
              Votes Abstaining               2,290



                                       2
<PAGE>   3

                    VALLEY FORGE CORPORATION AND SUBSIDIARIES
                                   Signatures


Pursuant to the requirements of the Securities Exchange Act of 1934, the
Registrant has duly caused this report to be signed on its behalf by the
undersigned thereunto duly authorized.

                                            VALLEY FORGE CORPORATION
                                            Registrant



Date:  January 5, 1999                      /s/ MONICA J. BURKE
                                            --------------------------------
                                            Monica J. Burke
                                            CFO and Vice President Finance



                                       3