There must have been an error somewhere, as I ordered my second army not to guard the Boneway but the Prince's Pass and the Reach border...
That is actually my mistake, it will be corrected right away!
Thank you! Now, should not have those raids in Dorne from the Reach been prevented, now that there was an army guarding that very border present?
Not necessarily, the raids were done by cavalry and with a series of instructions which favored quick raids. Considering the actual distances we're talking about (it's easy to forget Westeros is larger than South America in size), an army can only do so much.
I could've sworn I called off the raids in my PM ordering the coup... but I may be mistaken.