The key point was that Kennedy challenged Nixon to a series of televised debates. It was the first televised presidential debate in American history.
In 1960, 88 % of American homes had television. About 2/3 of the electorate watched the first debate on TV. Nixon was recovering from a knee injury, he looked drained. Kennedy, meanwhile, had been resting in a hotel for an entire weekend, he looked tan and confident.
Most Americans watching the debates voted for Kennedy, most radio listeners seemed to give the edge to Nixon.
After the baseball game, the mayor of the town went under the fence to receive his pizza.
The correct version of these two sentences when combined is:
When we were in Europe on vacation, we usually flew on airplanes: however, sometimes we took the train.
We apply the semi-colon to indicate that they have different ideas, and that they are clauses being joined into one sentence.
I need the entire sentence for context before I can answer the question. All of these options could be a subject, but you need to give context.