Short answers, pulled from the story.
Military funding began to significantly shape scientific research during World War I, when it marked the first large-scale mobilization of science for military purposes. Prior to the war, military-directed research and development was minimal in both the United States and Europe. The scale expanded dramatically with World War II, particularly through the Manhattan Project and radar research.
World War I is called the chemists' war both for the extensive use of poison gas and for the critical importance of nitrates and advanced high explosives to the war effort. Germany introduced chlorine gas as a weapon beginning in May 1915, drawing on the capacity of its powerful dye industry. Scientists on both sides then raced to develop more potent chemicals, including phosgene, tear gases, and mustard gas.
Porton Down was a British military research facility built from scratch during World War I for the development of gas weapons. Unlike most earlier military-funded ventures, research at Porton Down did not stop when the war ended. Chemical weapons development continued through the interwar years and into World War II, and Porton Down remains a significant military research institution into the 21st century.
The Manhattan Project became the model for future military-scientific work in the United States and beyond. After Japan's surrender, the project's infrastructure was too large to dismantle and became a permanent arm of the government as the Atomic Energy Commission. The pattern of large government-funded laboratories - some university-managed, some government-run - persisted through the Cold War.
In his 1987 article "Behind quantum electronics: National security as a basis for physical research in the United States, 1940-1960," Paul Forman argued that military funding had initiated a qualitative change in the purposes and character of American physics, not merely expanded its scope. He and others contended that military technologies formed the basis for subsequent research even in basic science, and that the culture of science was altered by extensive collaboration with military planners. Daniel Kevles disagreed, arguing that scientists retained intellectual autonomy and that military funding represented an expansion of opportunity rather than a corruption of scientific values.
Most of the basic component technologies for digital computing were developed through the Whirlwind-SAGE program, a military effort to build an automated radar shield. Virtually unlimited funds enabled two decades of research, though the final SAGE system had only marginal military utility. The culture of computer science was permeated with a Cold War military perspective, and through the mind-computer analogy, those ideas also reshaped psychology, cognitive science, and neuroscience.