Cardinal Richelieu manages to persuade the Duke of Savoy to sign
the Treaty of Susa. By this agreement, Duke Charles Emmanuel
permits French troops to pass through his territory on their way to
fight in the War of the Mantuan Succession.
Citation:
Editors. "Duke of Savoy signs Treaty of Susa".
The Literary Encyclopedia. First published 01 February 2011
[http://www.litencyc.com/php/stopics.php?rec=true&UID=16004, accessed 20 May 2013.]