Japan was at war during the Sengoku Period between 1467 and 1590, as feudal lords vied for supremacy.[7] Matchlock guns were used extensively and had a decisive role in warfare. In 1549, Oda Nobunaga ordered 500 matchlocks to be made for his armies. The benefits of firearms were still relatively questionable however compared to other weapons. At the time, guns were still rather primitive and cumbersome. According to one estimate in 16th century Japan, an archer could fire 15 arrows in the time a gunner would take to load, charge, and shoot a firearm.[8] Effective range also was only 80 to 100 meters, and at that distance, a bullet could easily bounce off armour. Furthermore, matchlocks were vulnerable to humid or rainy conditions as the powder would become damp.[8] However, firearms could be manned effectively by farmers or non-samurai low-ranking soldiers.[9]
The Japanese soon worked on various techniques to improve the effectiveness of their guns. They developed serial firing technique to create a continuous rain of bullets on the enemy.[10] They also developed bigger calibers to increase lethal power.[10] Protective boxes in lacquerware were invented to be able to fire matchlocks in the rain,[11] as well as systems to accurately fire weapons at night by keeping fixed angles thanks to measured strings.[12]
As a result, in the year 1567, Takeda Shingen announced that "Hereafter, the guns will be the most important arms. Therefore, decrease the number of spears per unit, and have your most capable men carry guns".[13] At the Battle of Nagashino in 1575, 3,000 arquebusiers helped win the battle, firing by volleys of 1,000 at a time, and concealed across a river and breastwork to effectively stop enemy infantry and cavalry charges while being protected.[14]
Japan became so enthusiastic about the new weapons that it possibly overtook every European country in absolute numbers produced.[9] Japan also used the guns in the Japanese invasion of Korea in 1592, in which about a quarter of the invasion force of 160,000 were gunners.[15] They were extremely successful at first and managed to capture Seoul just 18 days after their landing at Pusan