It's interesting in this context to note that McClellan too ended up under pressure to act soon. The Union government was very, very bad at assessing impartially whether it was time to act "now" instead of "later", and that resulted in Lincoln commanding an offensive across the continent in February 1862 (Washington's birthday, in fact).Little Mac is often criticized for having "the slows", but when he first took command he was right to insist on taking time to properly prepare and train the army.
In any year that would have been a bad idea; in 1863 and 1864 the campaign season in the East was considered to open properly in May, for example. In 1862 it was even worse as the weather in 1862 was some of the worst in recent history (California was basically underwater, there were horrible storms in the Atlantic, and so on). This pretty much came to nothing from logistic problems, but the "as early as possible" remained, and while McClellan's army was trained well enough (mostly) by the first quarter of 1862 he ended up effectively forced to take the offensive at least a month before the weather should have allowed; the result was that the Peninsular Campaign was repeatedly delayed by intense rainstorms.