William Franklin replaced Montgomery Meigs as the engineer in charge of the doming of the Capitol and building the Capitol extension late in the Buchanan administration. However the politically savvy Meigs rigged Franklin's ouster and his own return to the project through the good offices of a new Secretary of War (and future Stanton hatchet man), Judge Holt.
Franklin's biography by Mark Snell, From First to Last, has this wonderful background information on Meigs' removal. I thought of it on seeing The Hill:
[Meigs] had been at odds with the Capitol architect, Thomas U. Walter. Much of the disagreement stemmed from Meigs' attempt to usurp Walter's authority as the architect. By 1859, matters were almost out of control, and problems between the two men caused work on the Capitol to be greatly retarded. Mr. Walter confided to a friend that "I have been in open war for more than a year contending for the dignity of our Profession against the assumptions and despotism of a military upstart who happens to have the power to annoy."That phrase needs to come out of retirement: an "upstart who happens to have the power to annoy."
p.s. Meigs, the engineer, eventually practiced architecture designing a "lodge" for habitation by cemetery superintendents (as shown, here).