Board Thread:Battle Nations Discussion/@comment-162.194.174.61-20140907172449/@comment-11090687-20140907175505

Acces the Units menu in the bottom right corner, and after that, select the Armies tab in the bottom left corner. You should see the retreating armies that you used in PvP. Click on the armies and click on Collect. If there's a countdown timer, wait until it's finished and collect.

Hope this helps! :)