It's certainly true that the general understanding among nominally Christian Spaniards these days is that 'El Cid was 'our' champion against the Moorish bad guys', and the fact that he switched from one side to another at different times is much less well-known.

I think the charitable explanation is that he was driven out of the Christian camp by political machinations at the court of Alfonso VI, and almost forced to join the opposing army.

Although it's also the case that there wasn't just one side fighting another - there were small factions and fiefdoms with shifting alliances within and between both Christians and Moors.

Another aspect of the Reconquest that I think it's hard for us to get our heads round these days is just how long the process was.

We think of the Thirty Years' War or Hundred Years' War as being astonishingly protracted conflicts, but from Pelayo waging the Battle of Covadonga in 722 to the fall of Granada under Ferdinand and Isabella in 1492, 770 years passed.

Spain was at least partly under Moorish rule for far longer than it has since been a nominally Christian, Western European nation.

And during that time political and military control, as well as linguistic and cultural predominance, shifted constantly across different parts of the peninsula.