Arquebus

Arquebus is a technology unique to the Portuguese that can be researched at the Castle in the Imperial Age in Age of Empires II: The African Kingdoms.

This technology allows Portuguese Hand Cannoneers and the Organ Gun unique unit to benefit from the accuracy boost of Ballistics.

Strategy
Arquebus is highly useful if the player favors the use of Hand Cannoneers and Organ Guns due to it increasing the accuracy of those unit at longer ranges. This lets them neutralize incoming melee units more effectively, thus remedying one of their major weaknesses.