An application for a concession for a standard-gauge railway, which had been prepared by engineer Jakob Ehrensperger from Winterthur, was submitted to the Federal Council in 1901.

The Swiss Federal Assembly granted the concession for a railway from Wil via Weinfelden to the state border at Konstanz on 19 December 1902.

The Grand Duchy of Baden State Ministry approved the entrance of the line into Konstanz station in 1903.

The initiative committee concluded a 15-year non-terminable contract for the construction and operation of a standard-gauge Wil-Weinfelden-Konstanz railway with the WeEG in 1906.

It sold its interest, in particular the interest-bearing bonds, to the AG für Verkehrswesen in Berlin Wilmersdorf, with a small proportion going to the Overseas Trust Corporation Ltd. of Johannesburg.

After the First and Second World Wars, the MThB was an important source of hard currency for German counterparties in the periods of high inflation.

The trains generally began and ended in Konstanz, where a connection to the German state railway network existed.

They used the 1 km-long Kreuzlingen–Konstanz line, which had been opened by the Swiss National Railway (Schweizerische Nationalbahn; SNB) on 17 July 1875 and later transferred to the SBB.

The chief executives were Peter Joss, longtime director, and Hermann Lei (a former member of the Grand Council of Thurgau).