Complex sentence: Even if the French were pushed back suffering losses, this did not prevent them from continuing and taking Kousséri; here they made a junction with the Lamy column (proceeding from Algeria) and the Joalland-Meynier column (proceeding from Niger).
Split into simpler sentences: Even if the French were pushed back suffering losses, this did not prevent them from continuing and taking Kousséri. Here, they combined with the Lamy column (proceeding from Algeria) and the Joalland-Meynier column (proceeding from Niger).