Following the union of Bulgaria with Eastern Rumelia, Serbia has
launched an invasion of Bulgarian territory, but has been speedily
defeated and humiliated. Now the Bulgarians launch a
counter-invasion of their own and take the town of Pirot in
south-eastern Serbia, but the intervention of Austria forces them
to withdraw.
Citation:
Editors. "Bulgarians are forced to withdraw from Serbia".
The Literary Encyclopedia. First published 30 December 2011
[http://www.litencyc.com/php/stopics.php?rec=true&UID=18923, accessed 24 May 2013.]