bull

Please help me to understand the meaning of "bull" in the context as follows:
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When first I had arrived at Abbasia Barracks in Cairo straight from a convoy from England, my 'draft' of RAG officers had been told by an immaculately dressed cavalry colonel (with only one arm and a DSO): 'Two things. Forget everything you have ever learned in England and learn to do as you are told.' No Sam Brownes, no polished buttons, no 'bull'.

bull = bullshit

In the British Army it meant exaggerated zeal for ceremonial drill, cleaning and polishing &c.

This sounds like a military situation, so I think that meaning would fit.

I don't remember hearing this bull, but the OED defines it as Unnecessary routine tasks or ceremonial; excessive discipline or ‘spit-and-polish’ (originally services slang).

The OED doubts whether this bull, or bull in the sense of nonsense, derive from bullshit (they are 'popularly associated with bullshit'). Bull in the sense of 'a ludicrous jest' or 'a self-contradictory proposition' date back at least to the first half of the 17th century, but bullshit is only attested since the 20th century.