[the_gipsy]

Their narrative would just change slightly, to not getting a "real" or "fair" referendum, one that they could win. And they would not be wrong.

Yes, sending the riot police was a very, very bad move in terms of defusing a conflict. Literally all they had to do is let them run their big show, and expectedly declare the result void. At most, prosecute the politicians that unilaterally proclaimed independence in the parliament based on that puppet referendum.

However, the political party in power at the time, Partido Popular, knew that they would win some (right/fascist) votes everywhere else in Spain by exceeding force in Catalonia, in a kind of "scorched earth" move. They historically got almost no votes represented out of Catalonia anyway.