Found the following article online, use it to answer the question: What society did the man who had poor command of the Czech language become chorus master of after returning from Sweden?  In 1861, it was announced that a Provisional Theatre would be built in Prague, as a home for Czech opera. Smetana saw this as an opportunity to write and stage opera that would reflect Czech national character, similar to the portrayals of Russian life in Mikhail Glinka's operas. He hoped that he might be considered for the theatre's conductorship, but the post went to Jan Nepomuk Maýr, apparently because the conservative faction in charge of the project considered Smetana a "dangerous modernist", in thrall to avant garde composers such as Liszt and Wagner. Smetana then turned his attention to an opera competition, organised by Count Jan von Harrach, which offered prizes of 600 gulden each for the best comic and historical operas based on Czech culture. With no useful model on which to base his work—Czech opera as a genre scarcely existed—Smetana had to create his own style. He engaged Karel Sabina, his comrade from the 1848 barricades, as his librettist, and received Sabina's text in February 1862, a story of the 13th century invasion of Bohemia by Otto of Brandenburg. In April 1863 he submitted the score, under the title of The Brandenburgers in Bohemia. At this stage in his career, Smetana's command of the Czech language was poor. His generation of Czechs was educated in German, and he had difficulty expressing himself in what was supposedly his native tongue. To overcome these linguistic deficiencies he studied Czech grammar, and made a point of writing and speaking in Czech every day. He had become Chorus Master of the nationalistic Hlahol Choral Society soon after his return from Sweden, and as his fluency in the Czech language developed he composed patriotic choruses for the Society; The Three Riders and The Renegade were performed at concerts in early 1863. In March of that year Smetana was elected president of the music section of Umělecká Beseda, a society for Czech artists. By 1864 he was proficient enough in the Czech language to be appointed as music critic to the main Czech language newspaper...
Answer:
Hlahol Choral Society