delivered the opinion of the court.

These five cases, althoúgh involvings separate transactions, may conveniently be considered in a single opinion. The suits were brought by the United States to annul certain land patents 1 issued under the homestead laws upon *401 the ground that the respective entrymen had defrauded the Government in securing the patents in that they had not actually resided upon the land and cultivated it as required by the statute, the statements in their proofs upon commutation being false. Rev. Stat., § 2301. It was further averred that the Wright-Blodgett Company, the appellant, at the time of its purchase of the respective tracts had notice through its agents of the fraud which had been perpetrated by the entrymen. The appellant answered in each case, disclaiming all knowledge of the alleged fraud and setting up that it was a bona fide purchaser for value after the issuance to the entrymen of the final receipts. The cases were separately heard and in each, upon pleadings and proofs, a decree was entered canceling the patent. Upon appeal, the Circuit Court of Appeals affirmed the decrees. The opinion of that court stated that it found ‘that fraud in the homestead entry’ was proved, and that the appellant was ‘charged through its active agents on the ground with knowledge of the fraud.’

*402 The appellant urges that it does not appear that the two courts concurred in their findings as the cases were decided in the District Court without opinion and, in three of the cases, there was testimony which, according to the Government, tended to show that the transactions were fraudulent not only because there had not been the residence and cultivation required by the statute and stated in the proofs, but also because of agreements prior to the commutation proofs to sell the lands to the appellant. But the District Court rendered its decree ip. the five cases on the same day; in two of these, it is not suggested that there was evidence of such anticipatory agreements, but the same decree was entered and must have proceeded on the evidence as to the lack of residence and cultivation. While the facts in the several cases vary in details they are so far alike in their main features with respect to residence and cultivation as to make it absolutely impossible to assume that any different conclusion of fact was reached by the District Court in the three cases than that at which it arrived in the two others. The two courts must be deemed to have concurred in their findings and in accordance with the well-settled rule their determination' upon mere questions of fact will not be disturbed, unless clear error is shown. Stuart v. Hayden, 169 U. S. 1, 14; Towson v. Moore, 173 U. S. 17, 24; Texas & Pacific Ry. v. Railroad Commission, 232 U. S. 338, 339; Washington Securities Co. v. United States, 234 U. S. 76, 78; Gilson v. United States, 234 U. S. 380, 384. An examination of the record fails to disclose any such error in the finding as to the fraud of the entrymen, and it is not necessary to recite the evidence.

It is insisted, however, that in the finding as to the standing of the appellant there was involved an erroneous application of the law. In substance, the argument comes to this, — that in a suit by the United States to cancel a patent upon the ground of fraud, where the land is held *403 by a grantee of the entryman, the Government must establish that the grantee' is not a bona fide purchaser for value; that this must-be shown by proof of a clear and cogent character; and that,, measured by this standard, the Government’s case was not made out. This contention proceeds upon an erroneous view of the governing principles as repeatedly set forth in the decisions-of this court. These principles may be briefly restated: Where a patent is obtained by false and fraudulent proofs submitted for the purpose of deceiving the officers of the Government, and of thus obtaining public lands without compliance with the requirements of the law, while the patent is not void or subject to collateral attack, it may be directly assailed in a suit by the Government against the parties claiming under it.' In such case, the respect due to a patent, the presumption that all the preceding steps required by the law had been observed before its issue, and the immense importance of stability of titles dependent upon these instruments, demand that suit to cancel them should be sustained only by proof which produces conviction. United States v. Minor, 114 U. S. 233, 239; Maxwell Land-Grant Case, 121 U. S. 325, 381; United States v. Stinson, 197 U. S. 200, 204, 205; Diamond Coal Co. v. United States, 233 U. S. 236, 239. And, despite satisfactory proof of fraud in obtaining the patent, as the legal title has passed, ’ bona fide purchase for value is a perfect defense. Colorado Coal Co. v. United States, 123 U. S. 307, 313; United States v. Stinson, supra; Diamond Coal Co. v. United States, supra; United States v. Detroit Lumber Co., 200 U. S. 321; United States v. Clark, 200 U. S. 601. But this is an affirmative defense which the grantee must establish in order to defeat the Government’s right to the cancellation of the conveyance which fraud alone is shown to have induced. The rule as to this defense is thus stated in Boone v. Chiles, 10 Pet. 177, 211, 212: “In setting it up by plea or answer, it must state the deed of purchase, the *404 date, parties, and contents briefly; that the vendor was seized in fee, and in possession; the consideration must be stated, with a distinct averment' that it was bona fide and , truly paid, independently of the recital in the deed. Notice must be denied previous to, and down to the time of paying the money, and the delivery of the deed; and if notice is specially charged, the denial must be of all circumstances referred to, from which notice can be inferred; and the answer or plea show how the grantor acquired title. . . . The title purchased must be apparently perfect, good at law, a vested estate in fee-simple. It must be by a regular conveyance; for the purchaser of an equitable title holds it subject to the equities upon it in the hands of the vendor, and has no better standing in a court of equity. . . . Such is the case which must be stated to give a defendant the benefit of an answer or plea of an innocent purchase without notice; the case stated must be made out, evidence will not be permitted to be given of any other matter not set out.” See also Smith v. Orton, 131 U. S., appendix, 1xxv, 1xxviii; Colorado Coal Co. v. United States, supra; United States v. California &c. Land Co., 148 U. S. 31, 41, 42; United States v. Stinson, supra; Story’s Eq. Pl., §§ 805, 805a, 806; 2 Pomeroy, Eq. Jur., §§ 745, 784; Jewett v. Palmer, 7 Johns. Ch. 65, 68; Seymour v. McKinstry, 106 N. Y. 230; Graves v. Coutant, 31 N. J. Eq. 763; Sillyman v. King, 36 Iowa, 207; Prickett v. Muck, 74 Wisconsin, 199; Bank v. Ellis, 30 Minnesota, 270; Lewis v. Lindley, 19 Montana, 422. In United States v. Detroit Lumber Co., supra, the Circuit Court of Appeals found that the Detroit Company was a purchaser in good faith and this court reviewing the facts reached the same result. The Company had no knowledge or intimation of wrong until long after the issuance of the patents. In United States v. Clark, supra, both courts below had found that Clark had no actual knowledge of the alleged frauds or of facts sufficient to put *405 him upon inquiry. Clark, his agents and advisers, testified that they did not know or suspect anything wrong. (200 U. S., p. 608.) The defense of bona fide purchaser for. value was completely made out and what is said in the opinion must be read in. the light .of that fact. Nothing was shown to impair the case which the defendant had established; and there was no intention to depart from the well-settled rule to which we have referred.

In the present case the appellant had its agents upon, the ground and it has been found that through these agents it had knowledge of the fraud. ‘The contention that as the Government had alleged notice through particular agents it could- not be shown that the Company had acquired knowledge through other agents, than those named is without merit; the allegation in the bill as to the particular agents was surplusage. Upon the question of fact, with respect to bona fides in its purchase, both courts below have found against the appellant and the record does not show any error requiring the reversal of the decrees.

Decrees ajfirmed.