What the Germans know. Jonny Blamey

It’s world war two. The Germans are occupying a French town and the British are going to attack at dawn, hoping to surprise the Germans. A British spy in the town finds out that the Germans know of the attack. Back at the British base the spy has this exchange with the British General:
SPY: “The Germans know we are going to attack at dawn.”
GENERAL : “Then we will call off the attack.”
ENTER PHILOSOPHER : “Why are we calling off the attack?”
GENERAL : “Because the Germans know we are going to attack.”
PHILOSOPHER: “But the German’s don’t know we are going to attack.”
SPY. “Yes they do, I heard them discussing it.”
PHILOSOPHER. “No, I mean that the Germans don’t know we are going to attack, because knowledge is factive, and we are calling off the attack. So it is not true that we are going to attack and therefore not true that the Germans know we are going to attack.”
GENERAL : “So the Germans don’t know we are going to attack?”
PHILOSOPHER : “That’s right, they don’t.”
GENERAL : “Then there is no reason to call off the attack.”
SPY (PEEVED) : “Look, if factivity is so important, I’ll rephrase it. The Germans know that we intend to attack at dawn.”
GENERAL : “Then we will call off the attack.”
PHILOSOPHER: “So we don’t intend to attack at dawn?”
GENERAL. “No.”
PHILOSOPHER. “Then the Germans don’t know that we intend to attack at dawn. Knowledge is factive, remember.”
SPY (Through gritted teeth): “Alright, you pedant, two hours ago when I was bravely spying on the Germans, I discovered that they then knew that we were then intending to attack at dawn, although they don’t know this any more.
GENERAL: “So they don’t know that we are now intending to attack at dawn?”
SPY: “I suppose not.”
GENERAL : “Then there is no need to call off the attack.”
PHILOSOPHER : “But if you don’t call off the attack, then they will know we are going to attack.”
SPY: “How about this, the German’s expect us to attack. Expectation is not factive, so they will expect us to attack whether we attack or not.”
GENERAL. “I haven’t got where I am today by underestimating the enemy. The Germans are in a state of constant readiness. They expect us to attack at all times. So of course they expect us to attack at dawn. What I want to know is whether they know we are going to attack at dawn.
PHILOSOPHER : Well, that’s up to you, if you call off the attack, then they don’t know, if you continue with the attack they do know. You see, knowledge is factive, so whether they know what we are going to do or not depends on what we decide to do.
GENERAL : “Look, I may be a military man of action, but I know a thing or two about natural science, and I know that we can’t affect the state of German intelligence in the town down there by these word games up here. Either the Germans know we are going to attack at dawn, or they don’t. Which is it?”
SPY : “They know we are going to attack.”
GENERAL : “Then we will call off the attack.”
PHILOSOPHER : “Do you see? Now they don’t know we are going to attack.”
GENERAL : “Get Out!”


PROBLEM
What do the Germans know? Does the answer to this question depend on whether the General decides to call off the attack? If so does this mean that knowledge content is external? I'm assuming that even if the British call off the attack, the Germans still know something. It is not as if they were wrong when they thought they knew the British were going to attack.