Final answer:
Defensive tactics in World War I changed drastically with the advent of new warfare technologies, making entrenchment and defense more effective than offensive attacks. This led to a key tactical shift where offensive strategies were largely abandoned for stronger defensive positions, highlighted by the deadly 'going over the top' assaults.
Step-by-step explanation:
Defensive tactics evolved significantly due to the new technologies of war that emerged during World War I. This historic shift from technique-based tactics occurred as armies recognized that offensive strategies were less effective than defensive ones given the advancements in military technology. With the introduction of trenches, machine guns, mines, and modern rifles, these defensive tactics provided a substantial advantage. Instead of charging, it became far more effective to entrench and defend a position. The concept of "going over the top" became notorious, indicating an attack where soldiers would leave the safety of their trenches to charge across no man's land, often resulting in heavy casualties without gaining significant territory.
Throughout history, military tactics have continually adapted, from the direct and indirect methods of attack mentioned by Sun Tzu to modern day tactics that deal with threats like terrorism. Groups such as ISIS have advanced their tactics to remain relevant on today's battlefields, just as countries did during World War I.