During 1915 and 1917, u-boats attacked not only enemy ships but also troops stationed close to shore. cities near the shoreline. german submarines. commercial supply ships.

Answer

But also commercial supply ships

Explanation

The U-boats were the boats used by the Germany submarines during the war.The U-boat means (under water boats ) which they used during word war 1 and even word war II. Being the very first country to use the submarines during the first world war.These boats were sent to the dangerous areas in the water without any escort and they still met their target. They attacked the enemy ships and also he commercial supply ships.

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