Upon the application of the widow of any Confederate soldier or sailor, or the widow of any Alabama soldier or sailor who served in the state in the War Between the States, the fact of her deceased husband's having served as alleged, and of his not deserting, may be proven by the affidavit of two reliable witnesses who are acquainted with the facts; or if such witnesses cannot be found, upon affidavit to that fact, it may be proven by any evidence that will satisfactorily prove the truth of such facts. Whenever the proof of such facts is made by evidence other than the affidavit of two reliable witnesses, such evidence shall be reduced to writing and subscribed and sworn to by the witness offering the evidence.