Warfare Along the Struma

By spring 1917 the British Salonika Force (BSF) was holding a 90 mile front, stretching from the River Vardar in the west to the mouth of the River Struma. Within this area the two main operational sectors were the tangle of hills and ravines west of Lake Doiran, where the nature of the terrain lent itself to the construction of strong defensive positions, and the Struma Valley, where a flat plain stretches between two ranges of hills standing between 5 and 12 miles apart. To the north of the valley lies the Rupel Pass, the entry / exit point to the valley through Beles Mountains.

In contrast to the formalized trench warfare practiced around Doiran, men of XVI Corps in the Struma Valley were employed on more mobile operations. Here there is little in the way of dead ground across a valley floor traversed by the Seres road, at that time, one of the few good roads in the region. When the British arrived in the valley during summer of 1916 the landscape consisted of a mixture of marshland, areas of thick scrub and patchworks of abandoned farmland surrounding small deserted villages. In addition the lower end of the valley was dominated by Lake Tahinos, now long since drained. Initially, the River Struma formed a natural barrier between the opposing forces.

British defences concentrated around crossing points on the river such as bridges, fords and ferries, with a number of outposts and bridgeheads on the eastern bank. To prevent enemy incursions towards these positions regular yeomanry and cyclist patrols were sent across the river. A major obstacle encountered during these patrols were fields of abandoned maize crops growing to heights of 6 – 10 feet, making it difficult to locate the enemy and keep contact with one’s own men. Indeed such crops proved excellent places in which to set an ambush.

In late September 1916, XVI Corps began a series of brigade-level operations in support of a major Allied offensive west of the River Vardar. British forces moved across the Struma in force, capturing a number of villages and establishing an outpost line where a more static form of warfare was put into practice. This is not to say that the offensive spirit was allowed to drop and patrols and raids were vigorously carried out. Even so, keeping troops active in the Struma valley was more difficult that at Doiran where the opposing trench lines were but a few hundred yards apart. The less aggressive nature of the Struma sector meant that, on average, troops remained in the line for up to 22 days. In contrast to Doiran, the rich dark soil, which had made the valley a fertile agricultural area before the ravages of the Balkan Wars (1912-13), lent itself perfectly to trench and dugout construction very much in the style practiced on the Western Front.

During the summer of 1916 it was quickly discovered that positions in the valley could not be held without unsustainable levels of sickness in the form of malaria affecting all units. This led British commanders to order an annual withdrawal to the foothills for the summer months. As the Bulgarians did likewise a huge expanse of no-man’s-land was created across the valley floor. Once again mobile troops came into their own, only this time yeomanry and cyclists were supported by ‘flying columns’ of infantry comprising one company per brigade area. These formations watched for enemy movements around villages and woods on their front and moved to eject such patrols from these locations.

With limited manpower, artillery and ammunition, Lieutenant General Sir George Milne (commanding BSF) could ill afford to conduct drawn out operations on a large scale. Needing to support the main Allied offensives west of the Vardar in 1917 and 1918 by attacking the Bulgarian stronghold of Doiran, operations in the Struma were inevitably destined to remain small scale. This was especially true as Milne was forced to strip much of the artillery from XVI Corps to provide anything approaching a sufficient bombardment force. Despite these limitations XVI Corps wrested the initiative from the Bulgarians and maintained it until handing over the Struma Valley to Greek forces during summer 1918.