Hobby time well spent in browsing old books.
So where did the Empire get the Landsknecht look which nowadays is held so dear by the old guard, us?
Back in early 1980s, Citadel worked with Ral Partha for a while. RP had a 25mm Renaissance range with Landsknecht style costumes. But that didn't leave any kind of lasting imprint on Citadel figures. I wonder if somebody built a Warhammer army with the RP Landsknechts already back then?
For the whole 1980s, the Citadel Fighters and accompanied RPG Human/Good lines followed a medievealesque/Tolkienesque fantasy look, with perhaps Italian/Burgundian late medieval/renaissance details, like vests and hats. Perhaps the armour was later 15th century, notably in the Big Fighters series. A couple of the Fighter figures had the puff. Slash was quite common actually. Early Elves also had some Renaissance in them. There were also Vikings, and a high medieval line with specifically 11th and 12th century figurines. So pretty much everything for Humans.
The 1987 edition, or the famous 3rd edition, introduced the WH Old World. It was followed in 1988 by WH Armies, which for the first time introduced fixed army lists for the game. (They were quite relaxed, with few obligatory units and a wide variety of possible allied contingents).
Browsing the 1987 rulebook, I found only one picture with Landsknecht inspiration:
The Empire list in 1988 had two obligatory units (in addition to the one obligatory character): Halberdiers and Crossbowmen. This is notably a 14th/15th century mainland Europe infantry combination, so 100YW, Hussite Wars, Burgundian Wars, and early Italian wars. The pictures for Empire do not have Landsknecht costumes:
The cannon clearly is of the early transportable type, 'medieval' or 'Burgundian':
So it looks like the introduction of a specific Empire entry with its specific troop choices did not create a Landsknecht style infantry look. Makes sense, because Citadel/GW had to keep selling their existing figures.
But the allies & mercenaries part of the 1988 Armies book gets interesting. Is the Halberdier wearing a later 15th century or even early 16th century Landsknecht style costume? The hat surely is boisterous:
The Estalian infantry is wearing 16th century 'Spanish' fashion:
And finally, we get even the 'landsknecht' word mentioned, with Nulner Landsknechtes
, even if the costume still echoes the existing Citadel Fighter line with less puff:
(He's the 1987 Dogs of War Cowden
, later an ordinary Fighter and then specified as a Spearman.)
So I guess this introduced the idea of Landsknechts in the Old World.
Interestingly, the first completely Landsknecht style figure set also came out in 1988, but not by Citadel itself. This was the Marauder MM61 Fighter Command. The rest of their contemporary Fighters still followed the late medieval look, but the 1991 MB1 Dwarf Regiment (with Spears!) had a the Landsknecht flavour.
Thus, the real change into Italian/Landsknecht costumes came with the completely new Perry line in 1991/1992, and the 4th ed Army Book. This also changed the Empire into a 1500 or early 16th century army, with new styles of artillery carriages, horse barding, and a prominence of handgunners (with the late 1990s Dogs of War locating the crossbow more in the south). But Empire completely lost pikes, and halberds stayed the hallmark of Empire infantry (at least in the background texts). So a peculiar combination of 15th and early 16th century arms and costume styles.
And this look started to wane already with the 7th ed State Troop figures, was it in 2007. The last puff & slash by GW were the current Greatswords, Huntsmen and the Empire/Freeguild General. Since then (the early 8th ed), the Perry brothers & the sculptor of the Greatswords have left GW, and Empire was officially overrun. I guess we need not hope for a Landsknecht revival by GW.
Interested to hear opinions & additions & corrections by the elders & other collectors.