Definition: This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.
Input: Realizing that war was imminent, Prussia preemptively struck Saxony and quickly overran it. The result caused uproar across Europe. Because of Prussia's alliance with Britain, Austria formed an alliance with France, seeing an opportunity to recapture Silesia, which had been lost in a previous war. Reluctantly, by following the imperial diet, most of the states of the empire joined Austria's cause. The Anglo-Prussian alliance was joined by smaller German states (especially Hanover). Sweden, fearing Prussia's expansionist tendencies, went to war in 1757 to protect its Baltic dominions, seeing its chance when virtually all of Europe opposed Prussia. Spain, bound by the Pacte de Famille, intervened on behalf of France and together they launched a disastrous invasion of Portugal in 1762. The Russian Empire was originally aligned with Austria, fearing Prussia's ambition on the Polish-Lithuanian Commonwealth, but switched sides upon the succession of Tsar Peter III in 1762.
Output:
What was Sweden's motivation to join the war?