At this moment, Mrs. Baines, a Salvation Army commissioner, arrives and meets Undershaft. She enthusiastically describes the work of the Salvation Army (even to the point of keeping the poor fed enough so that they won't strike against the capitalists), and she ecstatically tells of the offer made by a man named Bodger, England's chief manufacturer of gin, beef, and whiskey. Bodger will give the Army five thousand pounds if a donor, or donors, can be found to match this contribution. Undershaft gladly writes a check for this sum, to the utter horror of Barbara and to the cynical amazement of Bill Walker, who asks her again: "What price salvation now?"
Barbara immediately tries to get Mrs. Baines to reconsider because so many of the people whom they attend to are people who have become drunkards because of Bodger's whiskey and gin. Mrs. Baines, however, answers that "Lord Saxmundham has a soul to be saved like any of us. If heaven has found the way to make a good use of his money, are we to set ourselves up against the answer to our prayers?" Both Undershaft and Mrs. Baines argue with Barbara — Undershaft pointing out that simply because less than one per cent of the poor misuse alcohol is no reason to blame the man who makes it; then Mrs. Baines wonders if "there will be less drinking or more if all those poor souls we are saving come tomorrow and find the doors of our Shelters shut in their faces." In fact, Lord Saxmundham is giving money to take away from his own business. Undershaft continues the argument because his contribution is to be used to bring peace on earth, and every time a war is halted, he will lose large amounts of money: "I am never richer, never busier than when the papers are full of war. Well, it is your work to preach peace on earth and good will to men. . . . Every convert you make is a vote against war . . . yet I give you this money to help you to hasten my own commercial ruin." He then presents the check, which is accepted with flourishes of drum sticks and tears of joy from all gathered round.
In the celebration that follows, Cusins is delighted with the paradoxical irony of the entire proceedings and calls for a great meeting at once so that Major Barbara can announce that the Army is saved — and saved because of Mr. Andrew Undershaft. Cusins then gets a flag and a trombone for Undershaft, instructing him to "Blow, Machiavelli, blow" as they are about to leave the shelter triumphantly.
Suddenly, Major Barbara announces that she can't come. She does not criticize Mrs. Baines, but instead, she takes her "Silver S brooch" from her collar and pins the badge on her father's lapel. They leave together to the cry of "Blood and Fire," with Undershaft crying, "My ducats and my daughter!" Cusins then cries out, "Money and gunpowder!" (the Undershaft and Lazarus motto), and Barbara, in a cry of despair, asks, "Drunkenness and Murder! My God: why has thou forsaken me?"
After they all have left, Bill Walker wants to retrieve his money, which was earlier not acceptable to the Salvation Army (according to Barbara), but to his dismay, he finds that it is gone and hears that the "pious" Snobby Price, after having made his public confessions, at "half past twelve . . . pinched [Bill Walker's] pound at a quarter to two." When Barbara promises to refund him his pound, Bill Walker will not be bought by her, and so he leaves again, taunting her with "What price salvation now?" Barbara examines her funds and talks Peter Shirley into accompanying her for a cup of tea to keep her from crying.
Everything has been leading up to this dramatic scene. As noted in the last scene, Major Barbara adheres to her principles. In the same manner that she would not let Bill Walker pay for his conscience, and in the manner that she would not accept the two pence and then later, she would not accept the ninety-nine pounds from her father because, according to her, the money was "tainted," likewise she is not willing to accept the five thousand pounds because, regardless of the sum, it comes from the same source. However, because of the huge amount of money to be collected, Major Barbara is defeated by outside forces; she cannot withstand the arguments of Mrs. Baines and the other Salvationists who look upon the donations of Bodger and Undershaft as the salvation of the Salvation Army. The central paradox is presented by Mrs. Baines (even though she is not intellectually aware of the paradox): Can "tainted money" be accepted to be used for the execution of worthwhile ends?
Part of the dramatic irony (which means that we, the audience, know things that one or more characters on the stage do not know) is that Mrs. Baines thinks that she has been successful in soliciting the five thousand pounds from Undershaft, but we, the readers and the audience, know from the preceding scene that Undershaft has announced his intentions of buying the Salvation Army. He first accomplishes this intellectually by pointing out that in a perfect society, he and Bodger would cease to exist — that is, in the ideal society that Major Barbara is working to achieve, there would be no need for the average person to resort to alcohol or to become an alcoholic; thus, Bodger, the distiller, is working against his own self-interests in giving money to an organization which advocates complete abstinence. Likewise, in the perfect society, there would be no need for munitions of any sort; thus, Undershaft's donation would destroy him if the Salvation Army is right and is persuasive in advocating peace on earth. But Undershaft's ultimate aim is to undermine Barbara's belief in the Salvation Army and thus to free her from its claims so that she can join him in his great socialistic design.
Mrs. Baines's argument for the poor must not be misinterpreted. She pleads for money so that the poor won't attack the rich. That is, if the poor are given just a small amount — enough to subsist on — then the capitalists will be free to continue their exploitation of the poor. Shaw would be totally opposed to this type of exploitation and would advocate the poor's revolting against the capitalistic class. Shaw, like others, is opposed to the Salvation Army's using food, confessions, or any type of "opiate" to salve the conscience of the masses into passively accepting the dictum that a poverty class is necessary in a capitalistic society. The reader should constantly be aware that, for Shaw, poverty was the worst of all crimes (the use of the term "crime" to apply to poverty is a highly controversial use of the word), and that all types of charity contribute to the acceptance of poverty as the natural state of existence.
Cusins, who says little in this scene but nevertheless supports Undershaft, constantly refers to Undershaft as a "Machiavelli" — that is, as a person who will use any means to get his way. Undershaft wants to win Barbara over to his side for the most altruistic reasons, and therefore he will use any unscrupulous means to accomplish this end, which is theoretically an end aimed at the betterment of the general state of humanity.
The final statements that ring so true are Bill Walker's statements "What price salvation now" and "I alit to be bought" because the salvation of Bodger and Undershaft costs them five thousand pounds each and Bill Walker offered only one pound, which had been both rejected and stolen from him, and whereas he had tried earlier to buy his salvation, he now throws the concept back at Major Barbara with his assertion that "I ain't to be bought" because now the Salvation Army itself has been bought.
Barbara's removing her Salvation Army pin and crying "My God: why hast thou forsaken me?" indicate that she has been defeated. How she will accept her defeat will be the subject of the next act.