N'DJAMENA (Reuters) - Militants from Islamist group Boko Haram attacked Chadian army positions in Gambaru, a town in northeastern Nigeria, on Wednesday, and were beaten back, Chadian military sources said."We knew they were going to attack us. We were waiting. The battle didn't last long. They fled," one military source told Reuters, noting that eight Chadian soldiers were wounded, three of 14 Boko Haram vehicles were destroyed and one was seized.Chadian troops are in Gambaru as part of a regional offensive against Boko Haram, whose militants have staged several cross-border attacks over the past week as part of its campaign to establish a caliphate.(Reporting by Madjiasra Nako; Writing by Matthew Mpoke Bigg; Editing by Louise Ireland)Join the conversation about this story Click here to read full news..