The
early years of Doctor Who did seem to like wholly historical stories
which in theory were easier to produce than sci-fi ones. While there would be
no issue with the Tardis landing amongst ordinary or fictional people, constant
encounters with well-known historical figures creates limitations on the
storylines. The BBC’s educational remit could be tested by depictions of the
likes of Marco Polo or Nero interacting with the Doctor while not all stories
are as strict about the effect the travellers have on history as `The Aztecs`
is. Its probably why the wholly historical adventures were replaced by pseudo
historical ones mixing supposedly real history with some alien antagonist.
Though generally intelligently written and made `The Crusade` harbours these
issues. All the way through you do get a sense that the production would be
more interesting without the Doctor and his companions in it at all. It sits at
the point where adherence to facts crashes into the need for some drama.