In 1939 Finnish Naval Forces [Merivoimat] was composed of Coastal Defence [Rannikkopuolustus] and Coastal Fleet [Rannikkolaivasto]. Coastal Defence led directly by Naval Forces Staff was composed of Coastal Artillery [Rannikkotykistö] and Coastal Infantry [Rannikkojalkaväki]. Strong Coastal Artillery was the backbone of the Finnish coastal defence and a relatively weak Coastal Fleet [Rannikkolaivasto] was intended to a mobile coastal artillery force with its new coastal armoured ships especially in the direction of demilitarized Åland Islands. Although weak in number coastal troops were a remarkable force with their heavy and super heavy long-range coastal guns.
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Coastal Artillery Units

In 1939 the largest coastal defence unit in Finland was a regional Coastal Sector (Rannikkolohko [or Lohko], Lo.). The whole Finnish sea coastline (about 1.600 km) was divided into ten coastal sectors. These independent coastal defence units were composed of the various number of Subsectors (Alalohko, ALo.) equal to an artillery battalion.

The defended area of a subsector was divided into Guard Regions (Vartioalue) supervised by coastal troops. On the most threatened and heavily defended areas along the Gulf of Finland coastline and passages were secured with coastal batteries which were usually in fortified bases called as Fort (Linnake, Ln. also Lke).

Fort had typically one or more Coastal Batteries (Rannikkopatteri, RPtri) with one to six guns in open or armoured positions. The oldest coastal batteries were in open line positions but modernized and new batteries were decentralized and camouflaged and in some cases there were also decoy batteries. Most new batteries had firing sectors of 360 degrees instead of the earlier limited one. Armoured batteries had usually armour shields open at rear but some of the heaviest 305 mm (12") batteries were in armoured single or twin gun turrets.

Coastal sectors and subsectors had usually subordinated infantry and naval units. Areas less suitable for a large scale invasion were only patrolled by infantry or motor boats of the Coast Guard [Merivartiolaitos] and local units of Civil Guard [Suojeluskunta].

In western Finland coastal sectors were under the command of two regional headquarters which commanded and conducted also naval units, naval traffic and subordinated naval air units (see from the Finnish Air Force 1939 - 1940 page). Aircraft operated in naval reconnaissance role detecting Soviet war ships, especially surfaced submarines.

Coastal Sectors and Forts as well as naval command HQs (from east to west and then northwards) were as follows:

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During the Winter War the northern shores of the large sea like Lake Ladoga was defended by a coastal unit called Naval Defence of Lake Ladoga (Laatokan Meripuolustus, LMe.P) (Commander Col. E. Järvinen). It was directly under the command of the Finnish Supreme HQ.
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Naval Infantry Units

There were no specialized coastal infantry units in Finland during the Winter War. Separate machinegun and bicycle companies as well as separate infantry battalions and one bicycle battalion were although subordinated to Naval Forces Staff for the coastal defence. These units were usually improperly equipped and armed with obsolete or non-standard weapons. Personnel consisted mainly of older age classes with the average age of over 30 years and officers were usually reservists.

These units were clearly rated as secondary troops but despite of that most of them were later transferred to the front where they fought as well as other Finnish units. All infantry units subordinated to and formed by the Naval Forces are described on the page Naval Infantry Units 1939 - 1940.
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Other Coastal Defence Detachments and Groups

Åland Islands

Åland Islands Group (Ahvenanmaan Ryhmä, AR) was formed in Turku in November 1939 for the quick occupation and defence of the militarily neutralized Åland Islands [Ahvenanmaa]. Group was under the command of Finnish Supreme HQ. It was composed of two parts: Detachment H (Osasto H, Os.H) and Artillery Battalion A (Patteristo A, Psto A, also A-psto) which was a coastal artillery unit and became the bulk of the coastal artillery troops of Åland Islands Sector (Ahvenanmaan lohko, ALo.) which was a former Coast Guard's Åland Islands District re-named on 2.12.1939.

Already at the end of November 1939 it was obvious that Hanko Peninsula was even more threatened by the Soviets than Åland Islands. Åland Islands Group was therefore suspended and halved into a new Detachment H (Osasto H) which was moved to Hanko Peninsula and Defence of Åland Islands (Ahvenanmaan puolustus, AP) of which troops were moved to Åland Islands. This new command HQ had only a few infantry units under its command in addition to Åland Islands Sector which was responsible of the coastal defence. They were part of the Naval Defence of South-West Finland (L-SMe.P).
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Hanko Peninsula

Detachment H (Osasto H, Os.H) (Commander Maj.Gen. E. Hanell, Chief of Staff Lt.Col. M. Stewen) with its core units Infantry Regiment 22 (Jalkaväkirykmentti 22, JR 22) (Lt.Col. E. Hagelberg) and II Artillery Battalion / Field Artillery Regiment 6 (II/KTR 6) (Commander Capt. A. Ilva) [8 - 76 K/02, 4 - 122 H/09] was moved to Hanko Peninsula since 30.11.1939. Detachment was subordinated to Naval Forces Staff.

Hanko Sector (Ha.Lo.) and all its infantry units were subordinated temporarily to Os.H. The task of the detachment was to repel enemy invasion attempts at Hanko and Lappohja region. When no invasion seemed to happen against the southern coast of Finland Os.H was suspended on 6.12.1939 and the major part of its HQ was transferred to north from Lake Ladoga where it became Detachment Talvela (Osasto Talvela, Os.T).

On 8.12.1939 Infantry Regiment 22 (originally from the 8th Division) was moved away and attached to 6th Division which was in reserve of Supreme HQ on western Karelian Isthmus. On 1.1.1940 6.D was re-named as 3rd Division and JR 22 became Infantry Regiment 9 (JR 9). 6th/3rd Division had earlier given its own Infantry Regiment 16 (JR 16) to Detachment Talvela.
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Bay of Viborg and Eastern Gulf of Finland

Naval Forces Staff was at first responsible of the defence of Bay of Viborg [Viipurinlahti]. Since February 1940 the initially weak coastal defence was hastily reinforced by forming new artillery units. Temporary artillery units at Bay of Viborg were equipped with guns without recoil system.

On 18.2.1940 Karelian Isthmus Army (Kannaksen Armeija, Kan.A) took the command of all coastal troops on this area. A new regional HQ called Viborg Coastal Sector (Viipurin rannikkolohko, Vi.RL also VRLo.) was formed on 28.2.1940. It was re-named already on 1.3. as Coastal Group (Rannikkoryhmä, Ran.R also RR) (Commander Maj.Gen. M. Wallenius, 3.3.40- Lt.Gen. L. Oesch). It had the following units under its command: Viborg Sector (until 7.3. only), 4th Division, Group Berg (Ryhmä B) (with Infantry Regiment 9, Separate Battalions 19, 20, 22, 24 and a few battalions of the Field Supplement Brigade) and Detachment Varko (Os.V) (with Separate Battalion 7 and Bicycle Battalion 5).

Hamina Group (Haminan Ryhmä, HR) (Commander Maj.Gen. E. Hanell) was formed on 7.3.1940 west from the Coastal Group (RR) between Vilajoki and the city of Kotka. Kotka Sector (KLo.), Combat Detachment Paalu (Tst.Os.P) and Viborg Sector (VLo.) were now subordinated to HR which was directly under the command of Supreme HQ. Viborg Sector and Combat Detachment Paalu were merged together on 11.3. but command arrangements were still under way when the Winter War ended on 13.3.1940.
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Sources: TALHI, VALPA2, PAUJY1, PAUJY3, LAPNI2, VALOL1, VALOL2, KESMA1, SUOLA, ARIRE, MIKPO1,
LYYRE1, TIIPU1, LAALA1