With the outbreak of the Great Northern War (1700–1721), the Polish–Lithuanian Commonwealth was officially outside the fighting parties (Denmark, Saxony and Russia against Sweden), despite the fact that the main burden of hostilities was on its territory. It was only in 1704 that its representatives concluded an agreement with Russia and in the following years they undertook a joint fight against the Swedish king Charles XII and the Polish and Lithuanian nobility cooperating with him. Soon the alliance turned out to be “difficult” for both sides. The Polish–Lithuanian Commonwealth obtained military and financial aid from Russia for the expansion of its army. Poland and Lithuania also counted on Russia’s help in regaining the Baltic lands occupied by Sweden, which were also sought by the Polish king and the Saxon elector Augustus II. The Polish–Lithuanian Commonwealth also counted on support in the event that Turkey tried to take back Ukrainian lands from it. On the other hand, Tsar Peter I was successful at the front over the years (including the Battle of Poltava) and strengthened his political and military position in Europe. The tsar also began to interfere in the matters of the internally quarrelsome the Polish–Lithuanian Commonwealth, trying to be an arbiter deciding its fate. Additionally, the prolonged stay of Russian troops there was a heavy burden for the Crown and Lithuania. The common paths of the Commonwealth and August II with Peter I slowly diverged. With the end of the war between Russia and Sweden in 1721, former allies were already enemies. Due to the very wide range of political, military, economic and religious issues, this article is only an introduction to the indicated issues. The author’s intention is to inspire researchers to undertake a new, or revive an already started, historical discourse on the Polish–Russian alliance during the Great Northern War (1700–1721).