On 30 September a Russian army of 20,000 under Peter Lacy arrived in Warsaw, and on 6 October a second sejm (composed of a smaller number of electors who had dissented from the previous election) proclaimed Augustus III king.

France, which had agreed to financially and militarily support Stanisław in his bid for the throne, was reluctant to send a fleet into the Baltic Sea since it was trying to avoid confrontations with Britain and the Dutch that might draw those neutral powers into the conflict.

General Lacy, required to leave large garrisons to deal with Stanisław's partisan supporters, marched 12,000 men to Danzig, which he began to besiege on 22 February 1734.

The fleet was recalled before it became clear that Stanisław would need some sort of assistance, over the objections of France's ambassador to Denmark, Louis Robert Hyppolite de Bréhan, Count Plélo.

Adam Tarło, a Stanisław supporter, led 8,000 men in an attempt to relieve the blockade; these were surprised by a detachment sent from the siege lines under Lacy near the town of Berent (present-day Kościerzyna) and repulsed.

With the arrival of heavy artillery and 10,000 Saxons in May, the Russians captured Fort Sommerschanz at the mouth of the Vistula River, but were bloodily beaten back in an attempt to storm the Hagelburg.

He reappeared at the capital of Prussia, Königsberg, whence he issued a manifesto to his partisans which resulted in the formation of a confederation on his behalf, and the dispatch of a Polish envoy to Paris to urge France to invade Saxony with at least 40,000 men.