Well, since you brought it up, I'll add my two cents to attack and defense values.
The defend/attack question is always mediated by technological status and type of opponent.
Before machine guns, the attack/defend question can go either way. If you have spammed artillery techs and have lots of artillery brigades, you will benefit from attacking. On the other hand, if you spam the defensive techs (strategic mobility and all that) and are sitting in forts across from your enemy, you can dig-in and stand against them.
But machine guns change everything.
If you are sitting at machine guns, prior to the research of BOTH bolt action rifles and barrels, defense is where its at. Defense values with machine guns are so high that a defensive strategy is almost always in order. (Note that when I say defensive, I mean letting the enemy initiate combat, fighting them defensively, and then overrunning them when they retreat.) The casualties alone will be very painful, even if they barely manage to win a battle here and there. Generals can modify this, of course, but building a 19th century version of the Maginot Line and defending it with machine guns and guards can be worth the time and effort.
However, barrels and bolt action rifles swing the pendulum in the other direction. Even a cursory examination of tank brigades will reveal their absurdly high attack values and lackluster defense values. Coupled with inventions that fire off bolt action rifles (and the tech itself), guards gain some decent attack values again, along with the improvements to artillery. Once you have both techs, you can go on the offensive again and maul enemies, provided you use tank brigades in large quantities, backed up with artillery brigades, in offensives. They are expensive, but well worth it.
One tech that does not swing the defensive/offensive pendulum at all is Gas Attacks. No matter what your situation, gas is so useful that I usually research Military Directionism ASAP in 1900 (make sure you have Organic Chemistry). Gas gives a +3 to die rolls in either attack or defense, making it the single most important tech when fighting countries that do not have it. But you have to assume that GPs will quickly gain immunity to gas, so you cannot factor it in to the discussion in any great way.
There are some exceptions to these rules. When fighting uncivs (except China), you can usually just attack all the time and wipe them out. It is to your advantage to keep pressing an offensive against uncivs because even if you have machine guns, you want to put them to flight and keep them on the run until they are wiped out. If you are fighting China, be prepared to fight at 10:1 odds in some battles. High technology helps, but you really should consider treating China with respect and always playing to your strengths when fighting her just like when you fight GPs. If you are not Japan or the UK, consider annexing something bordering China to act as a staging ground for annexing bits of China rather than conducting amphibious landings. Even machine guns won't necessarily save you from 10:1 odds in battles. (But poison gas will)
The defend/attack question is always mediated by technological status and type of opponent.
Before machine guns, the attack/defend question can go either way. If you have spammed artillery techs and have lots of artillery brigades, you will benefit from attacking. On the other hand, if you spam the defensive techs (strategic mobility and all that) and are sitting in forts across from your enemy, you can dig-in and stand against them.
But machine guns change everything.
If you are sitting at machine guns, prior to the research of BOTH bolt action rifles and barrels, defense is where its at. Defense values with machine guns are so high that a defensive strategy is almost always in order. (Note that when I say defensive, I mean letting the enemy initiate combat, fighting them defensively, and then overrunning them when they retreat.) The casualties alone will be very painful, even if they barely manage to win a battle here and there. Generals can modify this, of course, but building a 19th century version of the Maginot Line and defending it with machine guns and guards can be worth the time and effort.
However, barrels and bolt action rifles swing the pendulum in the other direction. Even a cursory examination of tank brigades will reveal their absurdly high attack values and lackluster defense values. Coupled with inventions that fire off bolt action rifles (and the tech itself), guards gain some decent attack values again, along with the improvements to artillery. Once you have both techs, you can go on the offensive again and maul enemies, provided you use tank brigades in large quantities, backed up with artillery brigades, in offensives. They are expensive, but well worth it.
One tech that does not swing the defensive/offensive pendulum at all is Gas Attacks. No matter what your situation, gas is so useful that I usually research Military Directionism ASAP in 1900 (make sure you have Organic Chemistry). Gas gives a +3 to die rolls in either attack or defense, making it the single most important tech when fighting countries that do not have it. But you have to assume that GPs will quickly gain immunity to gas, so you cannot factor it in to the discussion in any great way.
There are some exceptions to these rules. When fighting uncivs (except China), you can usually just attack all the time and wipe them out. It is to your advantage to keep pressing an offensive against uncivs because even if you have machine guns, you want to put them to flight and keep them on the run until they are wiped out. If you are fighting China, be prepared to fight at 10:1 odds in some battles. High technology helps, but you really should consider treating China with respect and always playing to your strengths when fighting her just like when you fight GPs. If you are not Japan or the UK, consider annexing something bordering China to act as a staging ground for annexing bits of China rather than conducting amphibious landings. Even machine guns won't necessarily save you from 10:1 odds in battles. (But poison gas will)