In 1862, after Wallachia and Moldavia were united to form the Principality of Romania, Bucharest became the new nation's capital city. In 1881, it became the political centre of the newly proclaimed Kingdom of Romania under King Carol I. During the second half of the 19th century, the city's population increased dramatically, and a new period of urban development began. During this period, gas lighting, horse-drawn trams, and limited electrification were introduced. The Dâmbovița River was also massively channelled in 1883, thus putting a stop to previously endemic floods like the 1865 flooding of Bucharest. The Fortifications of Bucharest were built. The extravagant architecture and cosmopolitan high culture of this period won Bucharest the nickname of 'Little Paris' (''Micul Paris'') of the east, with Calea Victoriei as its Champs-Élysées.