Question

trench warfare began after germany failed in its initial plan to
seize france and bring a quick end to the war.
negotiate a temporary truce with the allied forces.

Explanation:

Germany's Schlieffen Plan aimed to quickly defeat France in the west before turning to face Russia in the east. When this plan failed, the war on the Western Front became a stalemate characterized by trench warfare. There was no initial plan about negotiating a truce with Allied forces, and the naval - attack was not related to the start of trench warfare.

Answer:

seize France and bring a quick end to the war.