“ The plaintiff is a minority stockholder of a railway company which owns and operates an interstate railroad, and that company is the sole defendant. The purpose with which the suit is brought is to enjoin the defendant company from carrying out an agreement with two other railroad companies under which the three, collectively styled 'New York Central Lines,' are to acquire a large number of locomotives for use on their respective roads in both interstate and intrastate commerce ”

“ On application by the three companies pursuant to section 20a, the Interstate Commerce Commission, after notice and investigation, made an order approving the agreement and authorizing the acts contemplated therein. ”

“ The suit was begun in a state court, and then removed into the federal court, on the defendant's petition, by reason of the diverse citizenship of the parties. Want of jurisdiction was adjudged, because the court was of opinion that the suit was essentially one to annul or set aside an order of the Interstate Commerce Commission made under section 20a of the Interstate Commerce Act, as added by Act Feb. 28, 1920, c. 91, 41 Stat. 494, § 439 (Comp. St. Ann. Supp. 1923, § 8592a) ; that the United States was a necessary defendant and had not consented to be sued in a state court ”