Final answer:
Impressment was a key factor leading to the War of 1812 because Americans were outraged by the British practice of forcibly conscripting U.S. sailors into the Royal Navy, which was seen as an affront to American sovereignty and personal liberties.
Step-by-step explanation:
The practice of impressment led to the War of 1812 mainly because Americans were angry that impressment was forcibly subjecting their citizens to serve in the British navy. During this time, Britain was deeply involved in the Napoleonic Wars against France and was in desperate need of manpower for their ships. As a result, British ships stopped American vessels, impressing sailors by claiming them as deserters from the Royal Navy even when they were American citizens. This violation of American sovereignty and the personal liberties of American sailors created public outrage and was a significant factor driving the United States into war with Britain. Additionally, the incident with the HMS Leopard in 1807, where a British warship fired upon and boarded the USS Chesapeake, intensified American resentment and led President Jefferson to enact the Embargo Act of 1807, which further escalated tensions with Britain.