(1)    Petition; hearing; trial on merits. In any action, where service of summons is made by mailing, a defendant, at any time within 15 days of receiving actual knowledge of the pendency of the action or of the entry of judgment against the defendant, if judgment has been entered, but not more than one year after judgment was entered, may, by written verified petition, on forms provided by the court, petition to set aside the judgment if one has been entered and for an opportunity to be heard upon the merits. Thereupon the court shall set the matter for hearing at a time that will give the parties reasonable opportunity to appear and, if judgment has been entered, shall stay all proceedings on the judgment. At the time of the hearing the questions raised by the petition shall first be heard and determined by the court. If the court grants the petition, the court shall proceed to try the matter upon the merits or, if judgment has been entered, shall vacate the judgment and proceed to try the matter upon the merits. If the court denies the petition, it shall, if judgment has been entered, revoke its order staying proceedings thereon or, if a judgment has not been entered, it may give the defendant opportunity to be heard upon the merits.

   (2)   Effect of actual appearance. This section shall not apply to a defendant who actually appeared and submitted to the jurisdiction of the court without filing application as provided in sub. (1).