I'll be interested to see if this thread goes anywhere. I've been engaged in a slow long-term project to line up the mechanisms found across the F&F family of rules.
For the uninitiated, …
1990: Rich Hasenauer publishes Fire & Fury (F&F), an ACW rule set using the Brigade as the basic building-block 'unit'. I've gained the idea that the mechanisms built on On To Richmond.
These rules were widely adopted, and naturally soon spawned variants for other contexts; to my mind, the most substantial of these would be Nick Dorell's 'Fire & Furia Francese' adaptation (published in WI) for mid-late 19c European warfare. (In time this was further developed to become 'Mit Blut und Eisen')
2005: With Hasenauers's blessing, Bill Gray adapted the F&F system for larger Napoleonic actions; the result was Age of Eagles (AoE). If imitation is the sincerest form of flattery, Gray's avowed homage to F&F was sincere indeed; while AoE necessarily introduced changes to account for the expanded dimensions, the structure and wording line up precisely for much of the text.
2010: At the same time, Hasenauer had been applying his F&F system to Division-level engagements, with the Bn as core table unit; the result was Regimental F&F (RFF). From early on, these rules were designed not just for ACW, but also for other American conflicts from 1776 on, in which the forces were comparatively small. Others have, successfully I believe, made them work for the Crimea and the hyphenated mid-19c European conflicts.
Bill Grey was meanwhile extending AoE back to 1700 onwards and forward as far as 1914, giving rise to Age of Honor and Age of Valor respectively. These are extensions to the Age of Eagles vehicle, rather than new systems.
2015: an updated edition of AoE appeared – AoE2 – incorporating some improving tweaks
2017: Hasenauer had by now come to the view that his experience with RFF called for a revision of the original F&F; the result was Brigade Fire & Fury (BFF). BFF borrows directly from RFF, particularly the Fire Tables, and the structure and wording is considerably improved.
SO the outcome is an acknowledged family of related rules, ideally for multi-player games: Age of ~ occupies the Grand-Tac level for large armies; F&F/BFF that for small armies or large Corps; RFF meanwhile covers tactical engagements between opposing Divisions.
But the field is actually more crowded. While not wishing to offend the authors in question, it seems clear that the first F&F also provided inspiration for others. Chris Pringle took a scalpel to it (almost Grande Armee-style) to enable two players to thrash out big 19c battles at home; the result was Bloody Big Battles (BBB). The War Times Journal had already done something similar with its Republique rules. I also think I detect the nearby presence of F&F in aspects of Bruce Weigle's 1870/59/66/71 series.
Long ago, I started to waste my free time by compiling a mega-matrix of the aligned texts of F&F, AoE(2), RFF, BFF and later BBB. The obvious temptation is to distill this bloated monster into a single coherent body of rules – at my preferred sweet spot of small armies or large Corps.
I suspect many TMP readers might be curious to see these pages, but I have no wish to antagonise the great minds named above or invite copyright suits. However, I'd welcome thoughts in detail from anyone who has been thinking the same way.