Final answer:
To demonstrate the fluctuation of presidential power, examples include President Abraham Lincoln's expansion of power during the Civil War, President Andrew Johnson's impeachment signifying a decline, and President Franklin D. Roosevelt's increase in power during the Great Depression and World War II.
Step-by-step explanation:
To illustrate how presidential power waxes and wanes, one can look at the tenure of President Abraham Lincoln, who, during the Civil War, expanded his war powers and issued the Emancipation Proclamation, which was a significant use of executive authority. Conversely, after the Civil War, during the presidency of Andrew Johnson, we see how power can wane as Johnson faced significant challenges and was eventually impeached, showing the limits of presidential power during reconstruction. Additionally, the presidency of Franklin D. Roosevelt during the Great Depression and World War II showcases the significant expansion of presidential power through the New Deal policies and wartime leadership.