SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D Under the Securities Exchange Act of 1934 (Amendment No. 4)* Oshkosh Corporation (Name of Issuer) Common Stock, Par Value $0.01 (Title of Class of Securities) 688239201 (CUSIP Number) Keith Schaitkin, Esq. Icahn Capital LP 767 Fifth Avenue, 47th Floor New York, New York 10153 (212) 702-4300 (Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications) January 6, 2012 (Date of Event which Requires Filing of this Statement) If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of Section 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box / /. NOTE: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See Rule 13d-7 for other parties to whom copies are to be sent. *The remainder of this cover page shall be filled out for a reporting person's initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page. The information required on the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes). SCHEDULE 13D Item 1. Security and Issuer This statement constitutes Amendment No. 4 to the Schedule 13D relating to the Common Stock, par value $0.01 (the "Shares"), issued by Oshkosh Corporation (the "Issuer"), and hereby amends the Schedule 13D filed with the Securities and Exchange Commission on June 30, 2011 and amended by Amendment Nos. 1 through 3 thereto (as amended, the "Initial Schedule 13D"), on behalf of the Reporting Persons (as defined in the Initial Schedule 13D), to furnish the additional information set forth herein. All capitalized terms contained herein but not otherwise defined shall have the meanings ascribed to such terms in the Initial Schedule 13D. Item 4. Purpose of Transaction Item 4 of the Initial Schedule 13D is hereby amended by adding the following: On January 6, 2012, Carl Icahn issued an open letter to the shareholders of the Issuer. A copy of the letter is filed herewith as an exhibit and incorporated herein by reference, and any descriptions herein of the letter are qualified in their entirety by reference to the letter filed herewith. ON DECEMBER 15, 2011, THE PARTICIPANTS (AS DEFINED BELOW) FILED A DEFINITIVE PROXY STATEMENT WITH THE SECURITIES AND EXCHANGE COMMISSION. SECURITY HOLDERS ARE ADVISED TO READ THE DEFINITIVE PROXY STATEMENT AND OTHER DOCUMENTS RELATED TO THE SOLICITATION OF PROXIES BY CARL C. ICAHN, A.B. KRONGARD, VINCENT J. INTRIERI, SAMUEL MERKSAMER, JOSE MARIA ALAPONT, DANIEL A. NINIVAGGI, MARC F. GUSTAFSON, ICAHN PARTNERS LP, ICAHN PARTNERS MASTER FUND LP, ICAHN PARTNERS MASTER FUND II L.P., ICAHN PARTNERS MASTER FUND III L.P., HIGH RIVER LIMITED PARTNERSHIP, HOPPER INVESTMENTS LLC, BARBERRY CORP., ICAHN ENTERPRISES G.P. INC., ICAHN ENTERPRISES HOLDINGS L.P., IPH GP LLC, ICAHN CAPITAL L.P., ICAHN ONSHORE LP, ICAHN OFFSHORE LP, AND BECKTON CORP. (COLLECTIVELY, THE "PARTICIPANTS") FROM THE SHAREHOLDERS OF OSHKOSH CORPORATION FOR USE AT ITS 2012 ANNUAL MEETING OF SHAREHOLDERS, BECAUSE THEY CONTAIN IMPORTANT INFORMATION, INCLUDING INFORMATION RELATING TO THE PARTICIPANTS. THE DEFINITIVE PROXY STATEMENT AND A FORM OF PROXY IS AVAILABLE TO SHAREHOLDERS OF OSHKOSH CORPORATION FROM THE PARTICIPANTS AT NO CHARGE AND IS ALSO AVAILABLE AT NO CHARGE AT THE SECURITIES AND EXCHANGE COMMISSION'S WEBSITE AT HTTP://WWW.SEC.GOV OR BY CONTACTING D.F. KING & CO., INC. BY TELEPHONE AT THE FOLLOWING NUMBERS: SHAREHOLDERS CALL TOLLFREE: (800) 6595550 AND BANKS AND BROKERAGE FIRMS CALL: (212) 2695550. Item 7. Material to be Filed as Exhibits 1. Letter to Shareholders of the Issuer from Carl Icahn, dated January 6, 2012 SIGNATURE After reasonable inquiry and to the best of each of the undersigned knowledge and belief, each of the undersigned certifies that the information set forth in this statement is true, complete and correct. Dated: January 6, 2012 ICAHN PARTNERS MASTER FUND LP ICAHN PARTNERS MASTER FUND II LP ICAHN PARTNERS MASTER FUND III LP ICAHN OFFSHORE LP ICAHN PARTNERS LP ICAHN ONSHORE LP BECKTON CORP. HOPPER INVESTMENTS LLC BARBERRY CORP. HIGH RIVER LIMITED PARTNERSHIP By: Hopper Investments LLC, general partner By: /s/ Edward E. Mattner ------------------------ Name: Edward E. Mattner Title: Authorized Signatory ICAHN CAPITAL LP By: IPH GP LLC, its general partner By: Icahn Enterprises Holdings L.P., its sole member By: Icahn Enterprises G.P. Inc., its general partner IPH GP LLC By: Icahn Enterprises Holdings L.P., its sole member By: Icahn Enterprises G.P. Inc., its general partner ICAHN ENTERPRISES HOLDINGS L.P. By: Icahn Enterprises G.P. Inc., its general partner ICAHN ENTERPRISES G.P. INC. By: /s/Dominick Ragone ------------------- Name: Dominick Ragone Title: Chief Financial Officer /s/ Carl C. Icahn -------------------- CARL C. ICAHN