Defensive Array and a Stratagem
The army continued their march as all of their troops were shielded by the defensive array, soon arrows start raining down on them, they simply bounced off the defensive array while some of them exploded upon impact, some exploded because the soldiers had skills that allowed them to do that, while others because they were a special kind of explosive arrow that the kingdom produced.
It did little to the defensive array however as the army simply continued their march, it seemed that they had complete confidence in the power of the defensive array and as such there was no reason for them to be overly cautious. The other items they had were also put to use, there were multiple cocoon-like devices amongst the army and with a simple infusion of mana they opened up as hundreds of arrows were launched from them.