At some point in the 12th or early 13th century a junior line moved a short distance away and built Liebegg Castle near Gränichen.

On 28 May 1241 Burkhart I of Trostberg and his relative Ludwig of Liebegg appear in a document as witnesses and unfree knights in service to the Counts of Kyburg.

In 1486 the Schultheiss and council of Bern decided to sell Trostburg along with its lands and serfs to Hans von Hallwil, the victor of the Battle of Murten.

Apparently fearing that Brugg was expanding its influence, the city of Bern quickly bought the castle and then sold it to a cooperative of wealthy Bernese citizens.

Bern retained the rights to high justice and some income, which they transferred to Lenzburg Castle.

In the early 20th century it was partly rebuilt by a German butcher, but World War I prevented project completion.