The defences of the Odrin fortress

The entire defensive system was divided into four sectors:

a) North-western Sector from the right bank of the Tundzha to the left of the Maritza;

b) Western Sector from the left bank of the Arda to the right of the Maritza;

c) Southern Sector from the right bank of the Maritza to the right of the Arda;

d) North-eastern Sector from the left bank of the Tundzha to the left of the Maritza.

In spite of its faults, the North-western Sector was the strongest. Its resistance hung firstly on the grounds conformation, then on correctly designed infantry and artillery positions, in concrete casemates and in a well developed road system. The Western and Southern Sectors had only field fortifications because their defensive power lain in the position itself. The North-eastern Sector proved to be the weakest, in spite of the favourable ground conformation. Its technical main lack depended on the absence of shrapnel-proof shelters for the sharpshooters and the incorrect setting of the barbed wire entanglements.

The North-western Sector (15 km) was considered as the probable attack front and was strongly fortified. It could be divided into a Northern and a Western Sections.

As a whole the defences of this Sector, even if tactically perfect, were not satisfactorily fortified. In 1912 the still unfinished strongpoints could be regarded only as simple field works, because they had no gorges, covered ditch walls, flanking ditches and only rarely had shelters for the sharpshooters in the breastworks. Due to the peculiar kind of ground, to the shortness of the fire front and to the small, unprotected ramparts, the garrison was not protected from the enemy gun-fire. There were lacks also in the permanent batteries: their casemates were not shell-proof and they could not bear up to their own fire. On the other hand the interval infantry positions and the shelters for the reserve behind the girdle were effective and the communications were flawless.

The Northern Section, lain on the height of Karagöz Tarla, was composed by two lunette redoubts, interval infantry positions and nine batteries, four of them equipped with 120mm and 150mm guns. The two redoubts were called Ešil Tepel (I) and Jasž Tepe (II) [fig. 1]. They were unfinished and visible from afar due to the light colouring of the breastworks (yellow earth). On the other end the infantry positions [fig. 2] were slightly visible and had a considerable resistance.

At approximately 40m from the redoubts there were barbed wire entanglements with a width of 10-14 m. They consisted of iron staffs from 1.2 to 1.8 m. height over the ground, with a distance of 1.5 to 2 m within the rows, and of 2 to 3 m between the rows. This type of obstacle was intensively used in the whole place; sometimes stakes had to replace the iron staffs. However the barbed wire entanglements without any gaps proved to be defective, because it prevented the garrison to support the fore field positions before the breach. For the protection of the guns crews behind the batteries shelters in wood and corrugated iron were built. For the crew of the whole Section there were underground concrete shelters [fig. 3 and 4].

The group Karagöz Tarla had an advanced work on the heights of Juči Tepeler. It was a sort of lunette, built to prevent the enemy artillery to occupy the crest, where it could carry out enfilade fire against the works of the Western Section. It was placed on a wide hill, 9 km far from Odrin. It was a redoubt without gorge, protected by three frontal and two lateral trenches, connected by zigzag communication trenches.

The Western Section granted an unrestricted overview over the attack field and contained the works of Šaitan Tarla (III), Kazan Tepe (IV), Kazan Küprü (V), 27 batteries and the interval infantry positions.

Šaitan Tarla, named also Karagöz Tabia [fig. 5 and 6], was an old redoubt with gorges, high breastworks, casemated hollow traverses, a covered way and defensive earth slopes. The barbed wire entanglements did not surround the gorges. Two shelters were attached at the height of the farthest and wing gorges similar to them depicted in fig. 3 and 4.

Kazan Tepe, which was 3 km far from Šaitan Tarla, was characteristic for its flat ditch directly coated by the breast [fig. 7 and 8] and for the numerous little shelters under the rampart [fig. 9 and 10]. It was arranged for artillery too. However it had no gorge and therefore it could not be looked as a girdle main work. In front of Kazan Tepe there is a barbed wire entanglement covering the front and the lateral sides of the fort and doubling the main entanglement, built about 50 m before. Kazan Küprü could hardly be considered part of the defensive system because it was unfinished and in 1912 represented merely an earth pile. The whole position was flanked by a great number of field intermediary works.

Behind the forts some concrete shelters under the crest were protected from direct fire by the ground itself and formed the waiting position. In front of the forts many simpler trenches assured with the forts themselves a degrading fire against enemy attacks. The lines of defence were connected by zigzag communication trenches.

The batteries were placed hidden in the ground at 150 to 200m behind the infantry positions. Some of them had permanent emplacements and were armed with 150mm guns and 210mm mortars in central pivot carriage. Thanks to this mechanism and to the small girdle diameter these batteries were able to support with their fire other threatened sectors of the girdle. However the vaults of the casemates had a thickness of only 45cm, and therefore they were not enabled to resist the 150mm shell of modern guns. Moreover the construction itself was not faultless, since the vaults was cracked by the vibrations of the guns own fire, so the foundation sunk and gradually the wall entirely collapsed.

In the villages of Kadin köj and Ekmekci köj, the Turks had arranged advanced works and emplacements for the field artillery. Behind the girdle the old works of Baš Yuk Tepe (VI), Kemer Tepe (VII) and Milet Tepe (VIII) with some field batteries formed a second line of defence. They protected some great barracks and the Odrin main arsenal, built at the end of the crest separating the Tundzha from its tributary Kemer. In third line, the old fort Hadirlik (IX) still existed. During the entire siege in this fort a wireless station was in connection with Istanbul.

The Western Sector (5 km), lain on the right bank of the Maritza up to the left of the Arda, consisted of a 100m high plateau with numerous flat crests, whose slopes descended dropped gradually towards the valleys. The most important of these heights was called Papas Tepe, after which this sector was designated. The position of Papas Tepe was very strong : it dominated both the attack field as well as the neighbour sectors, which it could effectively support by flanking fire. It was protected by a field strongpoint for a battalion and by barbed wire entanglements. On 1 km westward on suitable crests advanced forward, defensive infantry positions for a regiment were arranged in order to protect the wings at the plateau slopes up to the Maritza and Arda. Such lines were arranged also east on the height Bekči Tepe. There were also two well placed batteries for 120mm field howitzers near Papas Tepe.

The Southern Sector (10 km) near the places of Karaăgac and Demerdeš had level ground, while southwest the ground rose : Kartal Tepe, 7 to 8 km far from Karaăgac, reached the height of 70m. Otherwise the ground was easily passable and could be easily covered by the fire of the batteries.

The girdle comprised 4 works and 13 batteries. In the Marica valley, the fort Bosna Tepe (X) lain in the village of Bosna köj, followed westward by Demerdeš Tepe (XI) [fig. 11 and 12], Karaăgac Tepe (XII) and Maras Tepe (XIII), then, between Demerdeš and Karaăgac, near the railway station, by the open work of Merkes Tabia (XIV).

All these forts were outdated and, in order to offer to the outskirts of Karaăgac with the railway station a better protection against the enemy fire, Turkish Army decided to advance the girdle further south and to build behind it some permanent batteries. At the beginning of the hostilities the new batteries [fig. 13 to 18] lain in front of the old forts. Infantry shelters connected with barbed wire entanglements were built forward them. From 5 to 7 km there were the advanced field works of Pamuk Serte, Tokad Bair, Kartal Tepe and Doudžaros : their position was well selected in the ground, but it was not easy for the batteries built 5 km backwards to support them.

The North-eastern Sector (16 km) was wide and could be divided into a Northern and a Eastern Sections.

In the North Eastern Sectors the favourable ground conditions were wasted for the lack of the necessary technical arrangements. The Turks tried to reduce this deficiency by the development of the advanced positions, achieving their goal only imperfectly because they were not able to provide an adequate protection for their troops and to separate the fore field positions from the main battle line sharply. Near Maslak the two positions joined up, so the enemy artillery could fire simultaneously to both. Only the battery of the girdle could support the advanced positions, since an incorrect arrangement of the barbed wire entanglements hindered the arrival of the reinforcements and the withdrawal of the first line troops. The occupation of the advanced positions delayed somewhat the bombardment of the city, but could not prevent the effects of the siege artillery fire. Probably it would be better to use the old forts only as observation posts and to shift the key of the defence to a more carefully arranged advanced line.

The Northern Section extended from Tundzha to the village of Arnaut köj. A tributary of the Tundzha, the Pravodisnitza, flowed through it in east-west direction. North of it the ground was flat, south it was more steep. The level ground was strongly fortified in order to prevent an enemy break-trough. So between the river and the Pravodisnitza on a level with the bridge over the Tundzha at Dertli Mustafa the Turks built infantry positions with shrapnel-proof shelters. A second line of such shelters were built on the northern valley heights running along the stream and in front of them there were 30 fougasses. The fort Kajalik Tabia supported the right wing of the second line (XV) [fig. 19 to 22] with an annex batter for field guns. It was situated south of the Pravodisnitza on a crest, whose foot could not be covered from the position. To remedy this gap the Turks dammed the stream up. South of it there was the Kurt Koej group with the works old Taš Tabia (XVI) and new Taš Tabia, supported by numerous infantry positions and several batteries. The old Taš Tabia, a 60 years old open redoubt, was situated 1 km behind the new work of the same name; this, 20 years old, presented only a lunette battery, but had brick casemated traverses and a shelter of the same material. The worth of this group laid only in the infantry positions, which were arranged for standing sharpshooters, but without shrapnel-proof covers. At 3 km behind the group, the works of Baši Tabia (XVIII) and Tašlik Altž Tabia (XIX) formed the second line [fig. 23]; they were built at the same time of the old Taš Tabia. The Northern Section included also the fort of Aivas Baba (XX), a work with an almost right-angled face that proved to be very disadvantageous in the attack. Some infantry trenches connected Aivas Baba with new Taš Tabia.

The Eastern Section began near the fort of Aivas Baba and extended to the Maritza. The main position lay on the crest, which ran almost in north-south direction, then approached the city up to 1.5 km and dropped in a steep slop. On this slop, the drinking water pipe led to Odrin. Tactically this position was strong, however it was fortified unsatisfactorily. Beside the infantry positions [fig. 26 to 28], it comprised 6 works and 27 batteries, Aiži Yolu (XXI), Kestenlik (XXII), Kuru Česme (XXIII) [fig. 24 and 25], Ildis (XXIV), Top Yolu (XXV) and Kavkas Tabia (XXVI), then furthermore Kaik (XXVII) on a narrow crest, 500 m east of the town.

All these forts were completely outdated: during their reconstruction in 1885 they received only brick casemates with covers 70 cm thick and over them an earth coating 27 – 28 cm thick. They had also breastworks 3.5 m height, which usually were surpassed by the hollow traverses, no flanking external ditches, but earth slops concealing covered ways. The distance of these works from each other amounted to 1 km on an average.

The batteries were placed in line in the intervals. Excepting few exceptions they were badly masked and owing to the wide dead angles they were not much fit for the direct fire. The majority of the heavy cannons was mounted on coastal carriages. The field positions for the artillery had shrapnel-proof covers of corrugated iron or wood and a wooden ammunition store. There were common shelters for groups of batteries and for the artillery duty of the whole Section a shelter 2 km west of the fort Ildis.

The short distance of this part of the girdle from the city and the care for the water pipe pushed the Turks to occupy and to secure advanced positions at 1 to 4 km eastward. At first they arranged only the peak of Kara Bair, later they fortified also the peaks of Maslak, Sapundzilar, Eski Kumluk, Demir Kapu and even the road to Istanbul. Between Demir Kapu and the fort Kavkas, they put even an interval work. These advanced positions consisted of infantry covers of various shapes, field batteries, linking way and shelters. They were separated from the main position not only by the valley, but also by barbed wire entanglements.

At the mobilization the Turks occupied some external positions at 2 – 2.5 km far from the main line of defence:

a) in the North-western Sector they started on the crest east of Kadin köj, turned before the mamelon south of Ekmekci köj, reached the advanced work of Juči Tepeler and, following the crest along the right bank of the Tundzha, ended near the river, north of the village of Havaras;

b) in the North-eastern Sector they started near the Tundzha, south of Havaras, reached the advanced work of Maslak, turned south, following the crest east of the girdle, crossed Mal Tepe and ended near the Maritza, behind the village of Bosna köj;

c) in the Southern Sector the positions were placed on the crest north of the Pamuk dere and, going on across the crests, reached the south bank of the Arda, south the village of Čerek köj, while advanced posts were established on the hill of Kartal Tepe and before the village of Doudžaros;

d) in the Western Sector the positions were placed approximately 1400 m before the hill of Papas Tepe.

These external positions were composed by unbroken lines of trenches with shelters, where the soldiers could usually fire on their foot, sometimes on their knees, but without strongpoints. Behind the crests where the combat positions were placed, the Turks built some shelters, with stoves and pallets, where the troops stood during the winter 1912-13. The defence and waiting lines were connected each other by covered ways and zigzag communication trenches.

There were emplacements for machine guns and artillery, but usually the external positions were armed only with field guns. There were only a few exceptions: in the Western Sector the head of artillery, Nuri bey, placed some howitzers batteries in the advanced posts, and in the Eastern Sector there were one 150mm howitzers battery at Mal Tepe and one 120mm howitzers battery at Mezar Tepe. The line of defence was somewhere protected by poor barbed wire entanglements.

The communications were generally sufficiently developed, especially in the North-western Sector, but they proved insufficiently on the Eastern front. The place possessed a well designed Decauville narrow-gauge railway (60 cm gauge), which proceeded from the arsenal and branched out in several radial lines. It had at its disposal 5 locomotives and around 200 field course cars of different models. There were some lorries too. The four Sectors were interconnected by means of bridges. Between the North-western and North-eastern Sectors there were four stone and two wooden bridges, two more in stone and wood were in the town. A single wooden bridge along the road Odrin-Karaagač connected these two sectors with the Southern one, while the railway bridge connected the Southern and the Western Sectors. The Western and the North-western Sectors possessed no connection with each other, just as little as the Western and the Eastern Sectors. This lack greatly hampered the running up of the reserves in the threatened areas. Nevertheless the Turkish Army originally had intended to build 118 iron bridges in the place and kept the material available; however this plan was not carried out.

The telegraph and telephone networks fully met needs. A wireless telegraph station was placed in fort Hadirlik. Underground cable directions connected the more important works with the telephone exchange, but there were telephone connections even between the forts. Besides a lot of volatile lines supplemented the permanent network.

Plans of the Turkish forts at Odrin