Task: Question Generation
Input (English): The Baltic was[when?] a forgotten theatre of the Crimean War. Popularisation of events elsewhere overshadowed the significance of this theatre, which was close to Saint Petersburg, the Russian capital. In April 1854 an Anglo-French fleet entered the Baltic to attack the Russian naval base of Kronstadt and the Russian fleet stationed there. In August 1854 the combined British and French fleet returned to Kronstadt for another attempt. The outnumbered Russian Baltic Fleet confined its movements to the areas around its fortifications. At the same time, the British and French commanders Sir Charles Napier and Alexandre Ferdinand Parseval-Deschenes—although they led the largest fleet assembled since the Napoleonic Wars—considered the Sveaborg fortress too well-defended to engage. Thus, shelling of the Russian batteries was limited to two attempts in the summers of 1854 and 1855, and initially, the attacking fleets limited their actions to blockading Russian trade in the Gulf of Finland. Naval attacks on other ports, such as the ones in the island of Hogland in the Gulf of Finland, proved more successful. Additionally, allies conducted raids on less fortified sections of the Finnish coast. These battles are known in Finland as the Åland war.
Output (English): When did the Anglo-French fleet join the Baltic attack?