George Canning's agreement to send troops to Portugal, to counteract Spanish threat of invasion in support of Dom Miguel, who is trying to obtain throne from Maria.
Citation:
Editors. "Britain supports Portugal against Spain by sending troops to Tagus".
The Literary Encyclopedia. First published 01 January 2010
[http://www.litencyc.com/php/stopics.php?rec=true&UID=4632, accessed 24 May 2013.]