give in. In November 1824 Württemberg agreed to an extension of the anti-liberal Carlsbad Decrees. After the successful French July Revolution of 1830, the Liberals were buoyant in most of Europe, as well as in Württemberg. The struggle for freedom in Poland against Russia in 1830/1831 reinforced this trend. In December 1831, the Liberals won the elections to the second chamber of the Württemberg Landtag. At the Hambach Festival on 27 May 1832, in which Hambach Castle in the Rhineland-Palatinate was a backdrop for liberal and democratic rallies, the call for banned political gatherings was answered. William moved to convene the parliament elected in 1831 for over a year until 15 January 1833. After the dissolution of parliament on 22 March, elections were held in April, and Friedrich Römer's liberals again emerged victorious. Diplomatic relations between Württemberg and Prussia and Austria were also limited at this time. From 1836 William tried to better relations with Prussia. In September 1836 Prince William, later German Emperor, visited Stuttgart. 1838 saw a return visit by King William to Berlin, where he and cousin, the Tsar Nicholas I met. From this point, a Prussian envoy in Württemberg was established. At various times Wilhelm was interested in forming a "Third Germany" of smaller states outside the control of Vienna and Berlin, but this never took form. One area of co-operation with Prussia was the Zollverein customs union. Wilhelm signed a Bavaria–Württemberg Customs Union (BWCU) in 1828, with mixed results. In 1828-34 the BWCU signed commercial agreements and then became full members of the German Customs Union. Seen now as a precursor of German unity under Prussia in 1871, at the time it was hoped that stronger local economies would preserve the independence of the smaller states such as Württemberg. The 1830s were characterised by an economic boom in Württemberg. Agriculture, trade and crafts flourished and debt and taxes were down. Shipping on the Neckar via the Wilhelmskanal had become possible in 1821, and the road network was expanded. Plans were produced for the construction of the first railways. William was very interested in the emerging industrialisation and visited, in 1837, the United Kingdom, the birthplace of the Industrial Revolution. For his Silver Jubilee in 1841, the kingdom was in excellent financial shape. On 27 September 1841 William celebrated his 60th birthday. On 28 September, a procession took place in Stuttgart with 10,390 participants, including 640