What is the irony in The Rose of Dixie by O Henry?

The irony in "The Rose of Dixie" by O. Henry lies in the fact that the members of the Rose of Dixie club, who are committed to upholding Southern ideals and preserving the memory of the Old South, unwittingly become victims of their own success when their advertisement leads to the commercialization and eventual demise of their club. This highlights the ironic outcome of their actions as they unintentionally contribute to the downfall of the very values they sought to protect.