Wis. Stat. § 75.39

A county, as the grantee named in any deed made by a county clerk, which conveys lands subject to a tax certificate which has not been redeemed may, at any time within 3 years after the date of such conveyance, commence an action against the person or persons owning the lands described in such conveyance at the time the lands were included in the tax certificate upon which such conveyance was made, or any parcel thereof or interest therein, or against any person or persons claiming under such owner or owners, for the purpose of barring such former owner or owners and those claiming under them of all right, title, interest or claim in such lands.