Speed

Ieme's heart jumped. 

None of the normal signs of an approaching enemy had been there. There wasn't an influx of Force, there wasn't an odd sound, there were no fluctuations in space… There was absolutely nothing. 

It took him a moment to understood, but he soon grasped it. There were none of those signs to grab a hold of because they weren't there to begin with. Those boats weren't being propelled by Force, they were being propelled by nothing more than wind and the rapid waters. On top of that, because they were using the water, their movements were masked by the rivers itself. It was no wonder none of them had realized that something was wrong until they were already so close.