A French war against both sides in Spain

What happens if both sides in the Spanish Civil War sink a French liner and France declares war on both?

France would face difficult land operations and diplomatic pressure, while Spanish territories in Africa would probably suffer most.

The scenario begins with both Spanish factions sinking a French liner and France declaring war on both. French forces are expected to encounter communications problems and difficult fighting in the Spanish mountains. The likely diplomatic reaction is treated as uneven: attacks on Republican forces would draw pressure to stop, while attacks on Nationalist forces might attract support. Spanish territories in Africa are judged especially vulnerable to French action. These are conditional outcomes within the proposed intervention scenario.