Task: Question Understanding
Input (English): Passage: The first Azov campaign began in the spring of 1695. Peter the Great ordered his army  to advance towards Azov. The army comprised crack regiments and the Don Cossacks and was divided into three units under the command of Franz Lefort, Patrick Gordon and Avtonom Golovin. Supplies were shipped down the Don from Voronezh.In 1693 the Ottoman garrison of the fortress was 3,656, of whom 2,272 were Janissaries.Between June 27-July 5 the Russians blocked Azov from land but could not control the river and prevent resupply. After two unsuccessful attacks on August 5 and September 25, the siege was lifted on October 1. Another Russian army  under the command of Boris Sheremetev set out for the lower reaches of the Dnieper to take the Ottoman forts there. The main fort at Gazi-Kerman was taken when its powder magazine blew up, as well as Islam-Kerman, Tagan and Tavan, but the Russians were not able to hold the area and withdrew most of their forces. By the Treaty of Constantinople  the remaining Russians were withdrawn and the lower Dnieper was declared a demilitarized zone.
Question: What happened first: Russians blocked Azov or Treaty of Constantinople?
Output (English): span