here is my proposal of the Israeli Tech tree, that could be implemented into the game. Commentaries on various tiers follow. Enjoy!
Commentaries and pictures:
.50 cal HMG
65mm 65M Modéle 1906
During the Second World War, Britain has left a number of armored vehicles in Africa, that were later - during the decolonization - sold or left to local armed forces. The ubiquitous Brencarrier was one of them and a number of them found their way to Palestine, where they primarily served with British armed forces until their withdrawal. A number of them were later either bought or captured by the newly emerging Israeli army and retrofitted with various weapons. While primarily an infantry carrier, Brencarriers (named after the famous light machine gun "Bren") were known to be modified to carry various heavier weapons. One of those could have been the famous French 65mm mountain guns, nicknamed "Napoleonchik" due their antique looks.
The first heavier weapons to reach Palestine to bolster the Hagana ("Defense") armed forces (that would later turn into regular Israeli army) were two of these obsolete guns. While not being absolutely obsolete, Jewish armed forces were absolutely desperate to get their hands on any heavier weapons they could get. Both of these guns were transferred to the defense of one kibutz ("community"), where they proved that even 40 year old weapons could dish out murderous firepower, when their fire routed an Egyptian armoured column heading for Tel Aviv.
This machine represents a hypothetical scenario - what if the Israelis mounted these guns on their Brencarriers? Brencarriers were also known to have 2pdr guns mounted in British service - the same thing could be done with the 37mm French guns the Israelis captured from damaged and destroyed enemy armed forces.
As you can imagine, finding a tier 1 vehicle for an army that started to exist in 1948 can be a real challenge. There weren't that many options here. Some obsolete infantry vehicles (such as the French tankettes that allegedly took part in some battles). The written sources on these early battles are rather scarce. The Bren is not heavily armored and the heavier gun can fire only forward. It is however fast and would play as a sort of "tank destroyer". Some people might note there is a more obvious choice for tier 1: the Vickers Mk.V/VI light tank, that was used by the Israeli forces (some were purchased, some captured from the Egyptians who used them). The reason for me choosing the Brencarrier is simply the fact that there is no weapon continuity in case of British weapons. If you pick the Vickers, you have no British variants for tier 2/3.
2pdr Mk. IX (pre war)
Renault R35 was not in the Israeli service per se, however, several pieces were captured from the Syrian army that used them. These R35's were retrofitted with British 2-pounder guns, that gave them some serious punch against the very light pre-war tanks. These R35's represent the early version with original engines. Syrian R35's took part in operations against newly-born Israel in the Galilee region, specifically against Degania kibutz on 20.5.1948, where the Jewish defenders knocked out and captured three of these machines. In 1982 however, more tanks of this type were captured by the Israelis, allegedly from PLO, who in turn got them from the Libanese army. One of these tanks was later moved to Saumur tank museum.
As you can see, there is a continuity from tier I via the 37mm SA18 gun, that was "mounted" previously on the Brencarrier. The R35 is already in the game, represented by tier II French vehicle. Apart from the armament, this vehicle is pretty much the same (after all, the Israelis and Arabs both used war surplus tech until the 50's). The 2pdr gives it a sort-of punch, but game-wise, it should probably play the same as the H35 the French have.
2pdr Mk. IX (pre war)
2pdr Mk. X (late)
Hotchkiss H39 was an improved version of Hotchkiss H35, which in turn was a counterpart to Renault R35. Both tanks saw service in the 1948 Israel Independence War. Hotchkiss H39 (using newer more powerful 120hp engine than the Syrian R35s) was also re-armed with a 2pdr. This tank saw action during the capture of Lydda airport by the 8th Armoured Brigade, after which it was re-armed from stock configuration with the 2pdr guns of various models. It continued to serve until 1956 - after operation Kadesh, all were believed to be scrapped.
This tank represents the third and final step of the "French" tanks. While slow and obsolete, the late 2-pdr with proper late war ammo (eg. adjusted armor penetration) should give it enough kick to hold its own on tier III. While some British and American tanks took part in the 1948 war and it would theoretically be possible to find a tier II/III counterpart (for example the Egyptian M-22 Locusts), the French line represents the biggest consistency. Of course, on tier III this tank would be rather weak even with an improved gun, but once you get over it to the "Sherman" part of the tree, things would get better.
75mm Krupp FH
75mm M3 L/37
Historically, the Sherman and its variants were the workhorses of the IDF for more than two decades. The first M4 Shermans to reach Israel were bought by the Jewish quartermasters from some scrapyard in Italy. They had their weapons removed by the Allies and so the first tanks to arrive in Israel were rearmed with salvaged 75mm Krupp howitzers (they were the M4A3 variant). Later, these would be upgraded back to the M4A3 Sherman standard. These tanks fought in the 1948 Independence War and when it ended, only 14 of 35 purchased remained operational.
As you can see, it's pretty much a "stock" M4 Sherman on tier IV with the stock tier V gun as its top option. The 75mm howitzer will be probably used to fire mostly HE ammo (eg. very poor penetration). I believe that a stock Sherman is just fine for tier IV, but it will probably be possible to slightly nerf its speed and turning rate compared to tier V, as the Shermans the Israelis bought were old and worn out.
105mm M4 Howitzer
The M1 Sherman (sometimes called "Super Sherman", though the name is generally associated with M-50 variants) was the mainstay of the IDF forces in the 50's. It's basically a stock M4A1E8 "Easy Eight" Sherman (or - in some cases - M4A3E8) with the long 76mm gun with (but sometimes without) muzzle brake. Actually there is no definite answer as to what type of tanks were "converted" into the M1 standart. Most of the Israeli M1 Shermans seem to be the M4A1 variants, but there are also pictures of the M4A3E8 and even some M4A4 variants with custom-mounted E8 suspensions. Generally, the M1 variant was in service until the late 50's, when the Shermans were converted into the M50 Super Sherman standard.
Yup, it's basically the "Easy Eight" on tier 5. With that, nerfs against the T6 E8 tank would have to come - specifically, the speed and turn rate (after all the M1's were acquired not new, but worn out), rate of fire nerf. Otherwise the tank would fit the T5 just fine - after all, the 76mm we can find even on the classic T5 Sherman.
M-50 Super Sherman
75mm CN 75-50
The M-50 Super Sherman came as a response towards the Arabian use of heavier and heavier Russian tanks, as Russia - previously friendly or even sympathetic to Israel - came to support the Arab countries more and more, pushing Israel steadily into the use of modern western tech. With Egypt,Syria and Jordan acquiring large number of T-34/85, IS and later even T-55 tanks, Pattons and Centurions, the older M1 variants became more and more obsolete. The M1 series 76mm guns were unable to penetrate these tanks at longer ranges and re-arming the Shermans became a necessity. The solution was to modify the Sherman turret to house the powerful French 75mm CN gun (which itself was a development of the German 75mm L/70 gun). The Israeli military officers liked the gun, but when offered French AMX-13 tanks equipped with it, they found the reload system of the AMX-13 unsatisfactory. Therefore plans were made to re-arm the Sherman with it and gradually, older M1 hulls of quite a few variants were fitted with the new turret, creating the M-50. M-50 saw debut in the 1956 during the Suez Crisis, when 180 M-50's were available under the command of Moshe Brill during the battle of Roeifa Dam. The tank later served during the 6-day War in 1967 and even during the 1973 Yom Kippur war, where they had trouble dealing with the heavier Centurions, T-55's and Pattons, leading to the development of M-51 Super Sherman. Please note that while the turrets and guns were gradually upgraded, the hulls were not and the Sherman hulls stayed the same for their entire time of service.
As written in the "history" section, the tank is still the same old Sherman hull (no armor upgrade at all!) with the new gun. The 75mm French gun was rather powerful and the rate of fire would have to reflect that, but game-wise this tank would be a mobile, hard-hitting yet quite fragile sniper.
M-51/M-60 Super Sherman
75mm CN 75-50
105mm CN 105D1
The ultimate Sherman evolution stage was the M-51/M-60 Super Sherman, or "Isherman" (as a shortcut of "Israeli Sherman"). As yet another reaction towards more and more heavily armored Russian designs employed by the Arab armies, IDF rearmed their Shermans with a shortened version of the French 105mm F1 cannon, designated D1. While not as powerful as the French original due to the Sherman turret size and recoil restrictions, M-51 Shermans still packed a tremendous punch. The cannon mainly used HEAT ammo, unaffected by the short barrel and massive muzzle brake. Additional counterweight was added to the turret to compensate for the added weapon weight. This tank served in the IDF until the late 70's, when most of them were bought by Chile. Chilean Army upgraded the Sherman even more, removing the massive CN gun and aplying the unique Israeli 60mm HVMS autocannon. While the cannon doesn't pack any special punch, it's penetration ability is massive, it's extremely accurate because of the ultra-high speed of the 60mm ammunition and the ability to fire in short bursts make it even deadlier.
This vehicle is quite special for its tier. While the mobility remains the same or lower as the previous Shermans, two distinctive play styles offer themselves. The 105mm gun is massive, rather slow firing (the turret is cramped for such a weapon) but very hard hitting. On the other hand, the 60mm weapon offers a low damage high penetration sniper autocannon. Please note that the hull armor remains the SAME from the tier 4 Sherman - there were no upgrades. That makes this machine rather fragile, yet the weapons should compensate for that.
Tier VIII - Tier X
Here it gets a bit more complicated. Basically, what's possible is to have 2 branches:
The Sho't branch (the Centurion versions) and the Tiran branch (captured T-54 versions). The Mag'ach branch (M48 Patton versions) is rather not possible as you have nothing to fill tier 8 and 9 with (the earliest Mag'Ach was the M48A1 version from Germany).
Sho't variants could be: tier 8 - original Ben Gurion (Sho't) Centurion Mk. 3 tank with 20pdr, tier 9 - Mk. 5 with L7 gun, tier 10 - Sho't Kal (uparmoured Mk. 5)
Tiran variants could be: tier 8 - Tiran 1 (rather unmodified T-54), gamewise with some nerfs making it about as strong as the Type 59, tier 9 - Tiran 4 (while technically practically identical to Tiran 1, game-wise it could reach the potential of T-54), tier 10 - Ti-67 (re-armed Tiran with an L7 gun - note that this gun could be common for both the Tiran and the Centurion branch).