How did the enemy defend itself against submarine attacks during World War 1?

During World War I, the enemy defended against submarine attacks primarily through the use of convoy systems, where merchant ships traveled in groups escorted by naval vessels. They also employed depth charges and mines to detect and destroy submarines. Additionally, advancements in anti-submarine warfare tactics, such as the use of hydrophones for listening and the deployment of patrol aircraft, enhanced their ability to locate and neutralize U-boats. These measures aimed to mitigate the threat posed by submarines, particularly by the German Navy.