thumbnail|right|Duchy of Courland and Semigallia in 1740 After Gotthard Kettler became the first duke, other members of the Order became the nobility, with their fiefdoms becoming their estates. Kettler received nearly one-third of the land in the new duchy. Mitau (Jelgava) was designated as the capital and a Landtag was to meet there twice a year.
thumbnail|right|duchy of courland and semigallia in 1740 after gotthard kettler became the first duke other members of the order became the nobility with their fiefdoms becoming their estates kettler received nearly one-third of the land in the new duchy mitau (jelgava) was designated as the capital and a landtag was to meet there twice a year