This document analyzes the effectiveness of Spain's lockdown measures in battling the spread of COVID-19. It finds:
1) The lockdown on March 14th significantly reduced the spread of the virus between Spanish provinces, indicating it prevented inter-provincial transmission.
2) Within provinces, the lockdown reduced the growth rate of coronavirus cases by an average of 5.8%, though effects varied between provinces.
3) A simulation found the lockdown prevented around 491,000 potential cases by April 4th, a 79.5% reduction from the scenario without measures.
4) Bringing the lockdown forward by one week could have prevented an additional 12.8% of cases,