Then you likely have your hero out on a tile (yielding resources).

When you send troops out, and you want to use your hero in the meantime, you can un-check the Hero (as marked in image) before sending.

Note: If you are doing battle you should *not* leave hero at home, but set hero at fighting skills etc.

Hero can also be set up with yielding skills etc. which improves the speed / capacity on *that* march by a lot - but you can not use hero both for yielding and attacking at once. It is restricted to once march.

There is an exception:

You can use one of the "Double Hero" boosts. With this you can send *two* troops with hero - or one troop with hero and a second for example hitting invaders. I would, however, be careful using these as they are few and far apart (all depending on packs you buy etc.)

But - point being a second hero can be very useful in battle as well as when you get knowledge up and start hitting 6's and ubers. That is: you can utilize 2x the time a march-boost and/or offence-boost lasts when slaying ubers for example.

If you havent been playing very long, its possible that you might  still have only got 1 march.

IF you have more than 1 march, you can send the hero to attack invaders  and use another for something else., like farming.

Theres a check box which allows you to send or not send the hero. ( and later on , the shaman on a mission).

Easiest way is to send the invader attack first, then use subsequent marches for other things