A Hotspot is an area of fighting, and is represented on the Continental Map by an animated yellow star. The presence of Hotspot stars are one of the main ways a soldier can gain information on where enemy forces are, and how active and numerous they are likely to be.
While a single Hotspot flash can be generated by something as small as a soldier shooting a Spitfire Turret with a Decimator, a wide spread of repeating flashes can indicate a large-scale mounted offensive.
The Hotspots are the primary method used to determine where a soldier making an Instant Action Request is sent.
Only action involving troops of a soldier's own Empire will be shown as Hotspots. Fighting involving only members of the other two empires will not be shown on the map at all. This can often create the impression that both the other empires are somehow at peace, and 'ganging up' on the third empire, but this is rarely the case.