In Duhig v. Peavy-Moore Lumber Co., Inc., 135 Tex. 503, 144 S.W.2d 878 (1940), W.J. Duhig purported to convey fee simple title to land by a general warranty deed and to reserve an undivided one-half mineral interest in the land. Id. at 878. However, unbeknownst to the grantee, on the date of the deed, one half of the minerals were outstanding in a third person--the estate of Alexander Gilmer. Id. The court held, under that fact situation, that: (1) the covenant of warranty extended to the surface of the land and one-half of the minerals; (2) there was a breach of the warranty; (3) that equity would estop Duhig and those claiming under him from asserting title against the grantee and those claiming under it. Id. at 880-81 ("Thus, the deed is so written that the general warranty extends to the full fee simple title to the land except an undivided one-half interest in the minerals."). The effect of the court's holding was to take the one-half mineral interest allegedly retained by Duhig and give it to the grantee in order to fulfill the covenant of general warranty. Id. at 880-81. Essentially, this allowed the grantee to get what it bargained and paid for, rather than having only a breach of warranty claim for damages. See id. at 880-81. The general rule set forth in Duhig was: "a deed purporting to convey a fee simple or a lesser definite estate in land and containing covenants of general warranty of title or of ownership will operate to estop the grantor from asserting an after-acquired title or interest in the land, or against the estate which the deed purports to convey, as against the grantee and those claiming under him." Id. at 880.