after stating the case, delivered the opinion of the court.

It appears by the proofs in the record that John F. Black-lock, the assignor of the bond, was, at the time of the assignment, a citizen of South Carolina, and continued to be such until this suit was commenced, and' that the defendant Small was, when this suit was commenced, a citizen of South Carolina. Under these circumstances, the provision of the 1st section of the act of Congress of March 3, 1875, c. 137, (18 Stat. 470,) applies to this case. That provision is as follows : “Nor shall any Circuit or District Court have cognizance of any suit founded on contract in favor of an assignee, unless á suit. might have been prosecuted in such court to recover thereon if no assignment had been made, except in cases of promissory notes negotiable by the law merchant, and bills of exchange.”

The present suit is a suit against Small, founded on contract, ■ namely, his bond and mortgage in favor of the plaintiffs, who claim only under the assignment made by their father, John F. Blacklock, to the defendant Bobertson. John F. Black-lock could not have prosecuted this suit in the Circuit Court of the United States for the District of South Carolina, to recover on the bond and mortgage against Small, if he had made no assignment of the bond to Bobertson, for the reason that he and Small were not citizens of different States when the suit was commenced, but were both of them at that time citizens of South Carolina.

In answer to this objection, it is contended by the appellants, that this suit is not to be regarded as a suit founded on the contract of Small, to recover thereon, but is to be regarded as a suit for the delivery of the bond and mortgage by Small to the plaintiffs, founded on their wrongful detention, and that the rest of the relief prayed by the bill is ancillary and incidental; and the cases of Deshler v. Dodge, 16 How. 622, and Bushnell v. Kennedy, 9 Wall. 387, are cited as authorities; but they do not apply.

The case of Deshler v. Dodge was an action of replevin, brought by" a citizen of New York against a citizen of Ohio, *104 in the Circuit Court of the United States for the District of Ohio, to recover possession of a package of bank bills. The title of the plaintiff to the contents of the package was derived by the assignment from corporations of Ohio. This court held that the action could be maintained, although the assignors could not have brought the suit, and that the suit, was not one to recover the contents of a chose in action- within the meaning of § 11 of the Judiciary Act of September 24, 1789.

In Bushnell v. Kennedy it was said, though not determined, because not necessary to that case, that the provision of the 11th section of the Judiciary Act of 1789 did not apply to a naked right of action founded on a wrongful act or a neglect, of duty, to which the law attached damages.

In the present case, the bill is clearly one for a decree against Small for the amount of the bond, and for a foreclosure of the-mortgage and a sale of the mortgaged premises.

There is another difficulty in the case, on the question of jurisdiction. The bond was a unit; the mortgage was a unit; and the assignment of the bond by Blacklock to Robertson in trust for the children of Blacklock .was a unit. The bond cannot be enforced against Small, nor can the mortgaged premises be sold, in favor of the two plaintiffs alone. The relief asked in the suit must necessarily be for the benefit of the defendant Helen Robertson Blacklock, as well as for the benefit of the plaintiffs, especially as, by her answer, she ranges herself on the side of the plaintiffs as against Small, joins in the prayer of the bill, and asks that the payment of the bond and the satisfaction of the mortgage be declared void, and that the bond and mortgage be declared valid in the hands of Robertson, as trustee, for the benefit of herself and the plaintiffs, and that Small be decreed to pay to herself and the plaintiffs the amount of money secured by the bond and mortgage, with interest. The suit is, therefore, shown to be one substantially by and for the benefit of Helen Robertson Blacklock, and the proofs show that, at the time of the commencement of the suit, she was, and has since then always continued to-be, a citizen of South Carolina, of which State-Small ^as and *105 is a citizen. Ayres v. Wiswall, 112 U. S. 187 ; Thayer v. Life Association, 112 U. S. 717; New Jersey Central Railroad Co. v. Mills, 113 U. S. 249 ; Louisville & Nashville Railroad v. Ide, 114 U. S. 52.

The Circuit Court ought, therefore, to have dismissed the bill for want of jurisdiction, and not upon the merits. For this error, its decree is reversed, with costs in this court against the appellants, because the reversal takes place on account of their fault, in invoking the jurisdiction of the Circuit Court when they had no right to resort to it, Mansfield, Coldwater & Lake Michigan Railroad v. Swan, 111 U. S. 379, 388, 389, and The case is remanded, to the Circuit Court, with a direction to dismiss the bill for want of jurisdiction, without costs of that court.