War & conquest.
It depends on the war.
If you are asking about the American revolution Spain gained nothing in the war.
Spain and the United states would gain nothing from a war. The two countries share cultural, political, economic, and militaryties, and are NATO allies. Such a war would never take place //
Parts of Spain.
The War of Spanish succession led most directly to Spain losing control of the Netherlands. This was a war between European powers on who to succeeded Charles II.
Between Spain and the US.
Adolf Hitler did not invade Portugal during World War 2 because Spain stood in the way. In order to invade Portugal, Hitler would have needed to go through Spain. Spain would not allow that. Spain had far more to lose than to gain by entering the war. Spain had colonies in Africa that the Allied powers could conquer and Spain had very little to gain by entering the war. Both Portugal and Spain stayed out of the war. Spain helped Hitler and Portugal helped England as much as possible without actually participating in the fighting.
Spain . Because they have better guns.
Spain and the US.
the war of jenkins's ear was fought between the British and Spain
The War was between Spain and the US.