Why would the game let you send an attack without any troops?

    This game is getting really tiresome. Amidst the 100+ nomad camps I spy everyday, i accidentally sent 1 as an attack instead of spy. Killing the spies and using up one of my daily attacks. Why would the game let a person launch an attack without any troops? It won't let you spy without any spies. Just stupid.

    I have done same myself, yes annoying, yes a waste of a free nomad attack but ALL troops can be used for attacking including bedouin ( spy ).
    I myself have used them to gauge an enemy who i cannot be asked to spy first to get a troops tally / report within