Maybe he was trying to drag and drop, or maybe he did really mean it how it was typed I don't know. He was trying to give the command to move the units closer. The same thing happened to me in the second or third c3 war I was using to get pop from. Oddly enough, nothing worked. I only kept getting the error "the map is outdated. The target doesn't exist anymore." Nothing worked at all, refreshing the screen, closing and re-opening, waiting until the next game month. I got frustrated and just declared on the neighboring c3 and ended the war in the other country.
The only thing I didn't do was try to use another browser.