Final answer:
The high-water mark of imperialism spanned from the late 19th century to the early 20th century, with European nations, Japan, and the USA expanding their empires through colonialism, notably in Africa with the 'Scramble for Africa'. The imperialist epoch was driven by economic competition and marked by extreme violence and exploitation.
Step-by-step explanation:
The high-water mark of imperialism is often recognized as the period between the second half of the nineteenth century and the early twentieth century.
During this era, industrialized nations such as those in Europe, as well as Japan and the United States, actively expanded their territories through colonial conquests and economic dominance over various regions around the globe.
The most notable was the "Scramble for Africa," which resulted in almost the entire continent being under European control in a remarkably short time frame.
These colonial powers also established their presence in Asia and the Pacific, with the British Empire being emblematic of this period as "the sun never set" on its territories.
In the Pacific, the United States acquired significant imperial possessions like Hawaii, Guam, and the Philippines. This period saw a rapid and aggressive expansion driven by the pursuit of raw materials, markets for finished products, and a sense of competition among the great powers.
Despite its later entry into territorial imperialism, the economic might of the United States played a role in driving European imperialism, as European nations sought to secure resources and markets to compete against the burgeoning American economy.
The imperialistic endeavors were also marked by significant violence and exploitation, with examples such as the brutalities in the Congo and the atrocities against the Herero and Nama in South West Africa serving as stark reminders of the era's dark legacy.