Exhibit 10.10

THIS CONVERTIBLE PROMISSORY NOTE (“NOTE”) HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “SECURITIES ACT”). THIS NOTE HAS BEEN ACQUIRED FOR INVESTMENT ONLY AND MAY NOT BE SOLD, TRANSFERRED OR ASSIGNED IN THE ABSENCE OF REGISTRATION OF THE RESALE THEREOF UNDER THE SECURITIES ACT OR AN OPINION OF COUNSEL REASONABLY SATISFACTORY IN FORM, SCOPE AND SUBSTANCE TO THE COMPANY THAT SUCH REGISTRATION IS NOT REQUIRED.

CONVERTIBLE PROMISSORY NOTE

Principal Amount: Up to $639,375

Dated as of [_] 2025

Renatus Tactical Acquisition Corp I, a Cayman Islands exempted company and blank check company (the “Maker”), promises to pay to the order of International SPAC Management Group I LLC or its registered assigns or successors in interest (the “Payee”), or order, the Principal Amount (as defined below) in lawful money of the United States of America, on the terms and conditions described below. All payments on this Note (unless the full principal is converted pursuant to Section 15 below) shall be made by check or wire transfer of immediately available funds or as otherwise determined by the Maker to such account as the Payee may from time to time designate by written notice in accordance with the provisions of this Note. For the purposes of this Note, the “Principal Amount” shall equal four hundred forty-two thousand five hundred ($442,500) dollars; provided that, to the extent the underwriters exercise their over-allotment option in connection with the closing of the Maker’s IPO (as defined below), as described in greater detail in the registration statement and prospectus filed with the Securities and Exchange Commission in connection with the IPO, the Principal Amount shall be increased by an amount equal to the product of (x) $196,875 and (y) the quotient of (i) the amount of units purchased by the underwriters pursuant to the over-allotment option in connection with the IPO divided by (ii) 2,625,000; provided further, that the Principal Amount shall be no greater than six hundred thirty-nine thousand three hundred and seventy-five ($639,375) dollars.

1. Principal. The outstanding Principal Amount balance (the “Outstanding Balance”) of this Note shall be payable by the Maker on (i) the Lock-up Expiration Date (as defined below) or (ii) the date that the winding up of Maker is effective (such date, the “Maturity Date”). The Outstanding Balance may be prepaid at any time, at the election of the Maker, without premium or penalty. Under no circumstances shall any individual, including but not limited to any officer, director, employee or shareholder of the Maker, be obligated personally for any obligations or liabilities of the Maker hereunder. For the purposes of this Note, the “Lock-up Expiration Date” shall mean the date in which the transfer restrictions set forth in that certain Letter Agreement, dated as of the date hereof, by and among the Maker and the Insiders named thereto (the “Letter Agreement”), with respect to the Founder Shares (as defined in the Letter Agreement) shall no longer remain in effect, such date being the earlier of (x) six months after the date of the consummation of the Maker’s initial business combination or (y) subsequent to the Maker’s initial business combination (A) if the last reported sale price of the Maker’s Class A ordinary shares equals or exceeds $12.50 per share (as adjusted for share sub-divisions, share dividends, rights issuances, reorganizations, recapitalizations and the like) for any 20 trading days within any 30-trading day period, commencing at least 150 days after the Maker’s initial business combination (B) or the date on which the Maker completes a liquidation, merger, share exchange, reorganization or other similar transaction that results in all of the Maker’s public shareholders having the right to exchange their ordinary shares for cash, securities or other property.

2. Interest. No interest shall accrue on the Outstanding Balance of this Note.

3. Drawdown Requests. The Principal Amount of this Note may be drawn down from time to time, in the sole discretion of the Maker, prior to the Maturity Date, upon written request from Maker to Payee (each, a “Drawdown Request”). Each Drawdown Request must state the amount to be drawn down, and must not be an amount less than Five Thousand Dollars ($5,000) unless agreed upon by Maker and Payee. Payee shall fund each Drawdown Request no later than five (5) business days after receipt of a Drawdown Request; provided, however, that the maximum amount of drawdowns collectively under this Note is the Principal Amount. Once an amount is drawn down under this Note, it shall not be available for future Drawdown Requests even if prepaid. No fees, payments or other amounts shall be due to Payee in connection with, or as a result of, any Drawdown Request by Maker. Notwithstanding the foregoing, all payments shall be applied first to payment in full of any costs incurred in the collection of any sum due under this Note, including (without limitation) reasonable attorneys’ fees, and then to the reduction of the unpaid Outstanding Balance of this Note.

4. Application of Payments. All payments shall be applied first to payment in full of any costs incurred in the collection of any sum due under this Note, including (without limitation) reasonable attorney’s fees, then to the payment in full of any late charges and finally to the reduction of the unpaid Outstanding Balance of this Note.

5. Events of Default. The following shall constitute an event of default (“Event of Default”):

(a) Failure to Make Required Payments. Failure by Maker to pay the Outstanding Balance due pursuant to this Note within five (5) business days of the Maturity Date.

(b) Voluntary Bankruptcy, Etc. The commencement by Maker of a voluntary case under any applicable bankruptcy, insolvency, reorganization, rehabilitation or other similar law, or the consent by it to the appointment of or taking possession by a receiver, liquidator, assignee, trustee, custodian, sequestrator (or other similar official) of Maker or for any substantial part of its property, or the making by it of any assignment for the benefit of creditors, or the failure of Maker generally to pay its debts as such debts become due, or the taking of corporate action by Maker in furtherance of any of the foregoing.

(c) Involuntary Bankruptcy, Etc. The entry of a decree or order for relief by a court having jurisdiction in the premises in respect of Maker in an involuntary case under any applicable bankruptcy, insolvency or other similar law, or appointing a receiver, liquidator, assignee, custodian, trustee, sequestrator (or similar official) of Maker or for any substantial part of its property, or ordering the winding-up or liquidation of its affairs, and the continuance of any such decree or order unstayed and in effect for a period of 60 consecutive days.

6. Remedies.

(a) Upon the occurrence of an Event of Default specified in Section 5(a) hereof, Payee may, by written notice to Maker, declare this Note to be due immediately and payable, whereupon the unpaid Outstanding Balance of this Note, and all other amounts payable hereunder, shall become immediately due and payable without presentment, demand, protest or other notice of any kind, all of which are hereby expressly waived, anything contained herein or in the documents evidencing the same to the contrary notwithstanding.

(b) Upon the occurrence of an Event of Default specified in Sections 5(b) and 5(c), the unpaid Outstanding Balance of this Note, and all other sums payable with regard to this Note, shall automatically and immediately become due and payable, in all cases without any action on the part of Payee.

7. Waivers. Maker and all endorsers and guarantors of, and sureties for, this Note waive presentment for payment, demand, notice of dishonor, protest, and notice of protest with regard to the Note, all errors, defects and imperfections in any proceedings instituted by Payee under the terms of this Note, and all benefits that might accrue to Maker by virtue of any present or future laws exempting any property, real or personal, or any part of the proceeds arising from any sale of any such property, from attachment, levy or sale under execution, or providing for any stay of execution, exemption from civil process, or extension of time for payment; and Maker agrees that any real estate that may be levied upon pursuant to a judgment obtained by virtue hereof or any writ of execution issued hereon, may be sold upon any such writ in whole or in part in any order desired by Payee.

8. Unconditional Liability. Maker hereby waives all notices in connection with the delivery, acceptance, performance, default, or enforcement of the payment of this Note, and agrees that its liability shall be unconditional, without regard to the liability of any other party, and shall not be affected in any manner by any indulgence, extension of time, renewal, waiver or modification granted or consented to by Payee, and consents to any and all extensions of time, renewals, waivers, or modifications that may be granted by Payee with respect to the payment or other provisions of this Note, and agrees that additional makers, endorsers, guarantors, or sureties may become parties hereto without notice to Maker or affecting Maker’s liability hereunder.

9. Notices. All notices, statements or other documents which are required or contemplated by this Note shall be made in writing and delivered: (i) personally or sent by first class registered or certified mail, overnight courier service or facsimile or electronic transmission to the address designated in writing, (ii) by facsimile to the number most recently provided to such party or such other address or fax number as may be designated in writing by such party or (iii) by electronic mail, to the electronic mail address most recently provided to such party or such other electronic mail address as may be designated in writing by such party. Any notice or other communication so transmitted shall be deemed to have been given on the day of delivery, if delivered personally, on the business day following receipt of written confirmation, if sent by facsimile or electronic transmission, one (1) business day after delivery to an overnight courier service or five (5) days after mailing if sent by mail.

10. Construction. THIS NOTE SHALL BE CONSTRUED AND ENFORCED IN ACCORDANCE WITH THE LAWS OF DELAWARE, WITHOUT REGARD TO CONFLICT OF LAW PROVISIONS THEREOF.

11. Severability. Any provision contained in this Note which is prohibited or unenforceable in any jurisdiction shall, as to such jurisdiction, be ineffective to the extent of such prohibition or unenforceability without invalidating the remaining provisions hereof, and any such prohibition or unenforceability in any jurisdiction shall not invalidate or render unenforceable such provision in any other jurisdiction.

12. Trust Waiver. Notwithstanding anything herein to the contrary, the Payee hereby waives any and all right, title, interest or claim of any kind (“Claim”) in or to any distribution of or from the trust account established with the proceeds of the initial public offering (the “IPO”) conducted by the Maker (including the deferred underwriters discounts and commissions) and the proceeds of the sale of the warrants issued in a private placement occurring prior to the closing of the IPO, as described in greater detail in the registration statement and prospectus filed with the Securities and Exchange Commission in connection with the IPO, and hereby agrees not to seek recourse, reimbursement, payment or satisfaction for any Claim against the trust account for any reason whatsoever; provided, however, that upon the consummation of the Maker’s initial business combination, Maker may repay the Outstanding Balance of this Note out of the proceeds released to Maker from the trust account after payment to holders of the Maker’s public shares. The foregoing shall bind any permitted assignee or transferee of this Note.

13. Amendment; Waiver. Any amendment hereto or waiver of any provision hereof may be made with, and only with, the written consent of the Maker and the Payee.

14. Assignment. No assignment or transfer of this Note or any rights or obligations hereunder may be made by any party hereto (by operation of law or otherwise) without the prior written consent of the other party hereto and any attempted assignment without the required consent shall be void.

15. Conversion.

(a) Notwithstanding anything contained in this Note to the contrary, at Payee’s option, at any time prior to payment in full of the Outstanding Balance, Payee may elect to convert all or any portion of the Outstanding Balance into that number of shares of Class A ordinary shares of the Company (the “Conversion Shares”), equal to: (x) the portion of the Outstanding Balance being converted pursuant to this Section 15, divided by (y) the lower of (i) $8.00 per share or (y) or the average daily volume-weighted average per share price of the Class A ordinary shares of the Company on Nasdaq as reported by Bloomberg L.P. over the 20 trading day period ending on and including the trading day prior to the date on which the Company is notified that this Note is to be converted, rounded to the nearest cent pursuant to this Section 15 (the “Conversion Price”), rounded down to the nearest whole number of shares. The Conversion Shares shall be identical to the shares of Class A ordinary shares, par value $0.0001 per share, included in the units issued by the Maker upon the consummation of the IPO. If prior to the Payee’s election to convert all or any portion of the Outstanding Balance into Conversion Shares, the Maker issues any subsequent convertible debt securities containing a conversion price per share less than the Conversion Price, the Conversion Price shall be, without any action on the part of the Payee, automatically adjusted to such lesser price per share. The Conversion Shares, and any other equity security of Maker issued or issuable with respect to the foregoing by way of a stock dividend or stock split or in connection with a combination of shares, recapitalization, amalgamation, consolidation or reorganization, shall be entitled to the registration rights set forth in that certain Registration Rights Agreement, by and among the Maker and the parties thereto, dated as of the date hereof, as further described in the registration statement and prospectus filed with the Securities and Exchange Commission in connection with the IPO.

(b) Upon any complete or partial conversion of the Outstanding Balance, (i) such amount shall be so converted and such converted portion of this Note shall become fully paid and satisfied, (ii) Payee shall surrender and deliver this Note, duly endorsed, to Maker or such other address which Maker shall designate against delivery of the Conversion Shares, (iii) Maker shall promptly deliver a new duly executed Note to Payee in the principal amount that remains outstanding, if any, after any such conversion and (iv) in exchange for all or any portion of the surrendered Note, Maker shall, at the direction of Payee, deliver to Payee (or its members or their respective affiliates) (Payee or such other persons, the “Holders”) the Conversion Shares, which shall bear such legends as are required, in the opinion of counsel to Maker or by any other agreement between Maker and Payee and applicable state and federal securities laws.

(c) The Holders shall pay any and all issue and other taxes that may be payable with respect to any issue or delivery of the Conversion Shares upon conversion of this Note pursuant hereto; provided, however, that the Holders shall not be obligated to pay any transfer taxes resulting from any transfer requested by the Holders in connection with any such conversion.

(d) The Conversion Shares shall not be issued upon conversion of this Note unless such issuance and such conversion comply with all applicable provisions of law.

IN WITNESS WHEREOF, Maker, intending to be legally bound hereby, has caused this Note to be duly executed by the undersigned as of the day and year first above written.

	Renatus Tactical Acquisition Corp I

	By:
		Name: Eric Swider
		Title: Chief Executive Officer

Renatus Tactical Acquisition Corp I S-1/A