Wheeler, J.

The action is brought to restrain the defendant Company from removing an ice-house from *532 the plaintiff’s premises. The plaintiff appeals from the judgment for the defendant, assigning as error the overruling of his claims: first, that at the time of this action the right of the defendant to remove the ice-house under its lease had expired; and second, that the judgment in the former case of the present plaintiff against Greene, Hall, and Ryder was not res adjudicata.

The lease provided for its termination, in case of sale of the premises during its term, on the first of October following the sale, and gave the lessee, The Milford Ice Company, the present defendant, the right to remove its ice-house from the premises leased within ninety days thereafter. Under the instruction and order of Greene, the general manager, of the Company, Hall and Ryder began tearing down this building when they, with Greene, were enjoined from so doing. The Company did not endeavor to remove the building until the injunction was dissolved and after the ninety-day period had passed; and the plaintiff claims its right of removal had expired, and hence the acts now complained of were unlawful. Greene’s order was the Company’s order, and Hall and Ryder were its servants, and therefore their acts were the Company’s acts. When its servants and agent, engaged upon its work, were enjoined from prosecuting the work, the Company could not continue in the work without violating the injunction order, if not in terms, surely in spirit. Until the injunction was dissolved, it could not lawfully remove this building, and so it was excused from carrying out the provision of the lease for the removal within ninety days from its expiration. The period covered by the injunction order was no part of the ninety-day period. That order suspended the running of this period. Immediately after the dissolution of the injunction, the Company began preparations for the removal of the building. The ninety-day period ran from the *533 date of dissolution of the injunction, and the Company had not forfeited its right of removal. The plaintiff's position is inequitable. He prevented the Company from removing the building within the period named; he cannot now be heard to complain because, through his act, the building was not moved within the period.

The main question raised by the appeal is, as the appellant insists, whether the judgment in the case against Greene, Hall, and Ryder estops the plaintiff from maintaining the present action against this defendant Company. That case, as well as this, is based upon a trespass upon the .plaintiff's premises. It is an admitted fact in each case that the defendants in the first action acted for the Company in the prosecution of its business. The lawfulness of their acts, and of the Company’s threatened acts of removal in this case, depends upon the right of the Company to remove the building, and that was determined by what its lease gave it.

The defendants justified in the first case under the Company's right of removal given in its lease. This issue, as were all others, was decided adversely to the plaintiff. Thus the real issue raised in that case was identical with that in this case, and the plaintiff in each action is the same.

In the present action the plaintiff insists that he is not concluded by the former judgment, since the Company was not a party to that action and it was not defended under the authority and in the right of the Company.

The general rule is undoubted: a judgment only concludes the parties to it or their privies. The rule has its seeming exceptions; but when analyzed they will be found to be apparent rather than real exceptions, applications merely of the general rule. The term “parties,” as used in this rule, includes not alone the nominal or record parties but the real parties in interest, *534 whose rights are involved and who can appear and direct and control the proceeding, those who in name conduct the litigation and those who authorize it or for whom it is conducted, as well as those who, by accepting as their own the acts and conduct of others, become bound by their consequences. McKinzie v. Baltimore & O. R. Co., 28 Md. 161, 166.

The trial court held “that a judgment in a suit in which an agent or a servant is a party prosecuting or defending, under the authority and in the right of the principal or master, is conclusive for or against the master.” This is sound law. The principle is an application of the doctrine of agency. Weld v. Clarke, 209 Mass. 9, 12, 95 N. E. 651. The defendants in the first action were the agents or servants of the Company, but the finding in this case does not set forth that they defended the action under the authority and in the right of the Company; and so the judgment in that case does not, for this reason, operate as a bar against the plaintiff. Nor is it found that the Company participated in the defense of the action in which it had an interest; had it done so, its conduct would have made it the real party in interest and the judgment have concluded it, as well as the plaintiff, as to all matters in issue. Heavrin v. Lack Malleable Iron Co., 153 Ky. 329, 155 S. W. 729.

Although these reasons are .ineffective, since the facts on which they must rest are absent from the record, there are other grounds for holding the plaintiff concluded by the former judgment. The work the defendants in that action were engaged in was the Company’s work. Greene was its general manager, consequently its general agent. His knowledge, obtained in the course of his employment, was the Company’s knowledge. When a principal or master has knowledge that his agent or servant is sued for acts done in *535 his service and within the scope of his employment, he must either become a party to the action, or defend the action through the agent or servant, or be concluded by the judgment rendered. After knowledge he becomes, whether he intervenes or not, a party in interest, having the same right to defend as the actual defendant and bound by the judgment thereafter rendered. Lamberton v. Dinsmore, 75 N. H. 574, 575, 78 Atl. 620; Rust L. & L. Co. v. Wheeler, 189 Fed. Rep. 321, 326, 111 C. C. A. 53; Rookard v. Atlantic & C. A. L. Ry. Co., 84 S. Car. 190, 65 S. E. 1047; Elliott v. Hayden, 104 Mass. 180, 182.

We think the Company was bound by the first judgment, and would have been bound had the judgment been adverse to the agent or servant. Since this is so, the objection of want of mutuality fails.

Were it not so bound, it might have the benefit of the judgment as an estoppel under a recognized exception to the general rule. Where, in actions of tort, the liability of the principal or master depends upon the culpability of his agent or servant, a judgment in favor of the agent or servant, in an action against the agent or servant for such alleged fault, may serve as an estoppel in favor of the principal or master when sued by the same plaintiff for the same cause of action. Portland Gold Mining Co. v. Stratton’s Independence, 158 Fed. Rep. 63, 68, 85 C. C. A. 393. When one knowingly sues an agent or servant, the judgment rendered in the action on the merits, whether for or against the agent or servant, in the absence of fraud, estops the plaintiff from thereafter suing the principal or master for the same cause of action. The principal and agent, or the master and servant, are “one in interest, and known to the plaintiff to be so.” Different reasons have been assigned by the many authorities so holding. The true reason, in our judgment, is found

*536 in the doctrine of election. A plaintiff has the right to sue either agent or principal, or both, or either master or servant, or both. If he chooses to sue the agent or servant alone, he must .abide by his choice. Liability for the servant’s or agent’s acts should be determined in a single action; the public interest and public policy require it, and private interests are thereby sub-served.

In Emma Silver Mining Co. v. Emma Silver Mining Co. of N. Y. Fed. Rep. 401, 408, a leading case, Choate, D. J., says: “While the principal, if he had no notice of the former suit, and no opportunity to defend it, may not be concluded by a judgment against his former agent, or made responsible for the agent’s bad pleading or blunders in the trial of the cause, because so to conclude him would be to deprive him of his property without due process of law, yet, as regards the plaintiff who has before sued the agent and been defeated, there is no reason why he should not be concluded upon that principle of public policy which gives every man one opportunity to prove his case, and limits every man to one such opportunity. He has had his day in court, and it is immaterial whether he has chosen to test his right as against the principal or the agent' in the transaction, provided the issue to be tried was identical as against both.” Priestly v. Fernie, 3 Hurl. & C. 977, 983; Emery v. Fowler, 39 Me. 326, 329; Rookard v. Atlantic & C. A. L. Ry. Co., 84 S. Car. 190, 65 S. E. 1047; Lindquist v. Dickson, 98 Minn. 369, 372, 107 N. W. 958; Anderson v. West Chicago Street R. Co., 200 Ill. 329, 333, 65 N. E. 717; Lake Shore & M. S. Ry. Co. v. Goldberg, 2 Ill. App. 228; Featherston v. Newburgh & C. Turnpike Co., 71 Hun (N. Y.) 109, 24 N. Y. Supp. 603; King v. Chase, 15 N. H. 9, 19; Bigelow on Estoppel (6th Ed.) p. 135; 2 Black on Judgments (2d Ed.) §§ 578, 579; 23 Cyc. 1265; note to 54 L. *537 R. A. 649. The authorities show that the same rule holds in tort as in contract actions.

The plaintiff herein, with a full knowledge of all the facts, elected, in the first action, to sue the agent and servants of the Company for acts done by them for it and under its authority, and the judgment then had, adverse to him, concludes him from maintaining this action against the principal and master for a cause of action already determined in the action against the agent and servants.

There is no error.

In this opinion the other judges concurred.