fortified line
line of troops and armament, fortified and set up to protect a high-value location during an armed conflict
en-GB/ˈfɔːtɪˌfaɪd ˈlaɪn/
en-US/ˈfɔɹtəˌfaɪd ˈlaɪn/
line of troops and armament, fortified and set up to protect a high-value location during an armed conflict