Take a look at this:
This is the rear in the laid-down position. At the right bottom, that large knob? Windage adjustment; it turns a pinion gear which meshes with teeth in the front of the sight and rotates it right or left; at the far left end you can see adjustment marks. Just right of the marks, see that hole? For 100 yards up to a couple of hundred, you were supposed to flip the ladder up and use the aperture for aiming. From that range(and there was an exact distance for these, but I'll look that up later, if I can find it again) on for a ways you used the notch in the base of the triangle above the aperture. For serious long range, that smaller knob is for elevation, loosen it and the whole notch/aperture setup slides up & down; please note that the elevation marks run all the way up to 2700 yards.
Now, if you look at the top of the aforementioned triangle, on the slider, you'll see a notch that's on top when the ladder is down, that's your battlesight. Remember I mentioned that most military rifles were set so that, with the sight in its' lowest position, it was actuall sighted for 300 yards/meters? Well, when this sight was designed for the original 1903 cartridge, it was. That one used a 220 grain roundnose bullet at about 2200 feet per second. Then the word came that the Germans had gone from a heavy roundnose bullet to a sharply-pointed bullet(spitzer) of much less weight, dropping from 220 to 150 grains. That allowed much higher velocity out of the Mauser, which meant a much flatter trajectory over distance, and- this bullet being more aerodynamic- longer effective range. So we did the same. The experiments led to the case being shortened .10", a 150 grain bullet was adopted at a velocity of about 2800 fps, giving us the ever-popular .30 Government 1906, later renamed the .30-06. However...
I can't remember the details(I do know where I can get a book that covers it, though) but the ballistics data for the new cartridge wasn't available in time for the sights to be made, so they were- mostly, at least- made with the markings from the 1903 cartridge. Which, with the higher velocity, more efficient projectile, meant that a battlesight originally designed for 300 yards actually was on at 500-something. Which means that at 100 yards, it's WAY high; where most are 3-6" high at 100, this hits about 8-10" high(rough numbers). And I have to point out that while that aperture for 'short' ranges works, that dinky little hole ain't worth crap in low light or bad weather(at least for me). Combine that with a thin front blade...
Gerry in comments brought up an old saying from WWI that the Americans had the best target rifle, the Germans had the best hunting rifle, and the Brits had the best battle rifle. Largely seems to cover it.
By the way, I've wondered for years, why did the Germans keep using that inverted 'V' front sight with the sharp point? THAT is also a bitch to use at times. The Swede Mausers use a similar, but it's got a flat top that's wide enough to use in low-light conditions, so why didn't the Germans use it?
For that matter, when the British were looking at a new rifle and designed the 1915(?) Enfield, I understand the different sights, but why did they go to a 5-shot magazine with it? The 10-shot of the #1 Mk3 worked so nicely, why change that?
Note: nice picture of 1903 sight found here, along with lots of other good pics of the rifle and parts.