The use of smoke may well vary with national doctrine, therefore any particular summary may not be applicable to all armies. 

 

However, in general smoke can be used to blind the enemy and screen own troops.  Best placing the smoke screen depends to some extent on the tactical problem and the required length of the smoke screen.  Sometimes if the enemy to be blinded is only a small position then placing the screen close to them may give the widest screening.  On the other hand if the enemy position is large it may be better to place the screen close to own troops, however, a moving smoke screen (which has been technically fairly simple since the introduction of computers in the 1960s) is seldom used. 

 

The key thing about a smoke screen is its length and duration.  Length is affected by the line of screen relative to the wind dirction (the gap between aimpoint will be relatvely close if the wind is blowing across the line of the screen, and will also affect how close you can place it to the enemy) but the type of smoke is also an issue (generally WP provides a shorter effective screen than other types).  Duration is obviously determined by how long you need to blind the enemy/screen youself.  Within that rate of fire is determined by windspeed and weather conditions.

 

Some armies will sometimes use a couple of guns firing smoke among the HE fire onto a target to enhance the smoke and dust created by HE.  Whether or not this is a good idea is a matter for the tactical (ie infantry) commander to decide.  There's pros and cons either way, and sensible competant armies aren't dogmatic.  Today it might also depend on whether or not the smoke is multi-spectral and whether or not both sides have devices to see thru non multi-spectral smoke.

It sounds like you are favoring the view that artillery delivered smoke is an opaque obscurant. If so, this make smoke a very powerful tool in shaping the battlefield.

 

If smoke is opaque then wouldn't it negate all ranged weapons? The early US doctrine defense of Europe depended on ranged fires against attacking Soviet columns (as the Israelis did against the Syrians in 1973). But if the Soviets could lay a barrage of smoke in front of their advancing armor wouldn't that render the American strategy completely ineffective?

 

The BMP1 73mm gun is no match for an M60 105mm gun at long range but at close range, it would be the equal of it. If the Soviets could sceen an advancing motor rifle battalion right up to the American tanks then the tanks are toast.

 

In effect, smoke becomes a cloak of invisibility for advancing troops.

 

 

 

Regarding the delivery of smoke, what would be the typical area (or length of line) that an artillery battery could create with continuous firing (allowing for replacing smoke that has disapated)?

There is absolutely no doubt that smoke is an opaque obscurant.  That has always been its main use.  The only issue is the type of smoke and part of the spectrum in which it is opaque.

 

If there is an effective smoke screen between a potential target that those looking at it then aimed or observed fire (by either side) is impossible.  However, a principle of defence is mutual support and the implication is that even if the enemy has blinded their objective they can still be engaged with direct or observed fire from elsewhere.  There are a couple of other issues, the extent to which residual smoke will adversly affect the attackers (eg disorientation, being unable to identify the defenders in detail, being unable to mutually support each other).  These factors will effect the defenders to a lesser degree, advantage to defenders.

 

Furthermore indirect fire against the attackers remains possible, it's just that the blinded observers cannot adjust it.  This of course assumes that an observer can adjust fire effectively against a moving target (and has time to do so).  A heroic assumption, you don't need to be a maths genius to work out that tanks moving at 30 kph cover 500 m in 60 secs.  It also invites the question as to how the observer knows/estimates how fast they are moving.  It's possible with a laser range finder and integral time measurement and a bit of maths.  Whether such LRF existed at the time is another matter.  Once you know the speed you can work out where to put the next rounds, but the target keeps moving while you're thinking.  In practice it's probably better to fire onto an area for a time and rely on the tanks driving into it. 

 

Depending on calibre and type of smoke a single gun can provide an effective screen of 200 - 400m.

 

I understand what you're saying. But as soon as ranged direct fire weapons open fire, whereever from, drop smoke on them. And if each gun can create a 200-400 meter screen then it shouldn't be too hard to cover all the suspect points during an assault.

 

I'm thinking here, for example, of the Syrian advance in 1973. They dropped all sorts of artillery fire on Israeli positions to little effect but smoke would have neutralized the long range Israeli fire allowing the Syrian assault to go forward unmolested instead of being picked off at long range.

 

It still seems to me that smoke is underutilized and underappreciated.

Not really sure what 'ranged' means related to direct fire systems.  If the assault is dismounted then indirect artillery is well capable of dealing with it, in the event that some attackers reach their objective it will become a short range infanrty fight.  As I said before, whether smoke helps or hinders attackers in these circumstances is moot.

 

If the attack is mounted then it can be engaged by direct fire from anywhere in range.  This could be 4 km or more once anti-tank msls come into play (and tanks come to that, and they may well move around to change their firing positions).  It's not at all easy to detect where these are coming from, particularly from a closed down vehicle surrounded by dust and smoke and the firers are to the flanks.  Making the heroic assumption that the attackers or their overwatch observers can detect where fire is coming from, the next question is whether there are available guns to engage in the time available before the attackers are on their objective. 

It depends on the type of smoke.  Those described as 'multi-spectral' are opaque to thermal imaging.