T he German-produced Montblancs are a tricky brand of pens to collect, mainly because most factory records were destroyed during the war. Also i don't pretend to know very much about Montblancs. I would also ask you to forgive possible disinformation given here, since some statements are based on pure conjecture.

In 1906 a German engineer namend Eberstein started business in Hamburg. The first pens to be produced were simple black eye droppers with slip-on caps and also gold nibs imported from the USA Eberstein very quickly found himself in financial troubles and it was only because he managed to find backers that the Simplo pen company was founded in 1908 in Hamburg, Germany.
   Their first pens were an attractive pen named Rouge et Noir (Red and Black) this because it was a safety BHR pen with a large red top. This pen initially came in eight styles:

Other than these the company offered a numnber of other models:

  In 1909 one of the financial backers suddenly died and shortly afterwards Eberstein was cought with his hand in the till and fled to America with his family to avoid legal action.
  The other backers managed to continue the company and in 1910 the sucessful Rouge et Noir got a brother. This model had a white cap top and this model became popular the top was within a few years changed into a stylized white star, supposedly for trade-mark reasons. The name of the new pen was Montblanc and the star is supposed to represent the snowy top of the mountain.
  During the period 1910-1924 a wide variety of Mont Blanc and Rouge et Noir-pens were produced. The Montblanc became so popular that the Rouge et Noir was discontinued in 1921, even though the companies Italian factory continued to produce it until 1923
The pens came in BHR or Mottled red/black HR:
At least the models 1-6 were also produced with octagonal bodies "to prevent rolling off the table".
Another model from this time was the Padrone, a bullet shaped pen which used an ink pellet with water added, much like the Parker "Trench Pen" and the Simplo was continued to be produced.
In 1921 One of the workmen at Simplo lefte the company and started kmaking his own pen, the Astoria after some years he ran into financial difficulties and his company was bought by Montblanc in 1932 who continued to produce Astoria pens until 1936, these are now quite rare.
  In 1925 the line was completely re-arranged and the above line was discontinued in favour af a new line that was graded into two classes: Top line and Bottom line, depending on price (and presumably on quality). The Top Line was called Meisterstück or (for export) Masterpiece, a pen that has found its way into our present day.
  On the top line the metric height of the mountain Montblanc (4810) was engraved first on then cap. The company tried a lot of filling systems but most early pens were safety pens (you were able to screw the entire nib into the pen body, this was safe for the nib - as long as you remembered to screw it in before you put on the cap - but inkwise the pens were rather messy) in the early 1920's they tried lever fillers: KOLLAS
  In 1929,inspired by Parkers Duofold-series, Simplo also began making button fillers side by side with the safeties, while the lever-fillers were discontinued. The new colours were: The Blue and Green are very rare.
The line in 1929 were: During this period a ball-ended clip in the shape of a teardrop was adopted when the costumer so wished.
  In 1932 an economy line was added. These pens came in three sizes denoted my an alphabetic letter, A, B or C.
  The Meisterstück pens now had the numbers 4810 engraved on the nib, while the economy line pens had the letters inside a small triangle, depending on the size of the pen.
  In 1934 the company changed its name to Montblanc-Simplo GmbH, and inthe same years the piston fillers were introduced a feature that still come with the Montblanc pens. In 1936 the famous Montblanc numbering systems were introduced (below) and the company got its first and only filling patent on the Kontrollfüller, a telescopic piston. A new clip with two ridges on top was adopted. Montblanc now produced a whole new series of pens and all previous pens were deleted from production: The marked pens should exist but i haven't seen them (for what that is worth). Simply the 3 digits stood for:
  The button fillers were slowly phased out in favour of the new piston-fillers. Around 1938 a new "stepped" clip was adopted.
  These pens from the mid 1930's are in my opinion the most attractive of all Montblancs. They have excellent balance, lies heavy and steady in the hand and are great writers. Only trouble is that new cork seals are a bit tricky to find.
  The early piston fillers had long ink-view windows with black bars painted inside, the later modls had shorter windows.
  In 1947 until 1959 a series of attractive Montblancs were produced in Denmark, many in colours and shapes not to be found among the german pens. Claus Holten are doing extensive research on these pens and i will not even try to describe them until he has presented his results (although we are waiting eagerly).
  In 1948 the new Meistersück pens were introduced and most models of previous years were discontinued, the 139 a notable exception. The new pens were more streamlined and much more slim, and they were all piston fillers with a rounded butt and the clipscrew the colour of the pen. These pens replaced their predecessors in the "130"-series.
  In 1952 the 244 and 246 were redesigned and now sported a more conical cap and a clip that was shaped like a spade. A new pen was the 149 that finally replaced the 139. The 149 is the longest surviving pens of all Montblancs since it is still produced and haven't much changed since the 1950's.
The pens in 1952 were:
  In 1955 the 240-series was replaced with the 250-series these pens had two cap bands with the lower one wider and covering the cap lip. They also had a new "cable"-clip. The nib was also redesigned into what has been referred to a "Flügelfeder"-nib. Also the 642, 644 and 742 pens in solid gold were deleted from production.
  The "340"-series was also redesigned and became more streamlined, the caps now had a single cap band and the nibs were more open.
In 1955 the colours were:
  In 1958 the Flügelfeder nib was adopted also on the Meisterstück pens.
  In 1959 the complete line was redesigned. The 142, 144 and 146 was discontinued ALL 3-DIGIT PENS? and the remaining pens were made slimmer and fitted with a new nib, the "Butterfly", so called because of its shape. The new pens came in two sizes only (excluding the 149).