The king had arranged, before his death, for a strengthening of
the alliance and personal union between the two countries via
the Union of Lublin which merged the separate Polish and
Lithuanian Parliaments and which provided for his own succession
by an electoral monarchy. Henceforward, the king of the
Commonwealth of Poland-Lithuania would be freely elected by the
nobility of both nations. On 16 May 1573, Henry Valois, third
son of King Henri II of France and of Catherine de’Medici, Duke
of Angoulême, Orléans, and Anjou was elected King of Poland and
Grand Duke of Lithuania. Several months prior to his election,
on January 28, 1573, the Polish Parliament in Warsaw went out of
parliamentary session and into the mode of a Confederacy (in
order to preclude the use of the Liberum Veto. The Confederacy
of Warsaw pledged the entire nobility of Poland-Lithuania not
only to refuse to enforce any measure by state or church
undertaking to compel religious conformity, but to resist
actively any such measure by armed fo