HISTORY suggests that even the most powerful leaders are apt to fail if they try to fight battles on too many fronts at once.
It is a lesson the Government should consider as it finalises its response to the widespread opposition to its plans for Performance-Related Pay.
Members of the National Union of Teachers are boycotting appraisals and the union has a conference mandate for a ballot on a one-day strike this term Even the moderate Association of Teachers and Lecturers has conference backing for possible industrial action to oppose performance pay. No one could seriously suggest that the NUT action will cause the Government to tremble.
Parents are unlikely to write to their MPs, complaining about the damage being done to their children by the suspension of teacher appraisals.
They may even welcome the fact that head teachers will have more time free from appraisal bureaucracy in which to run their schools. Of course, it may be that the unions' reaction turns out to be more bark than bite.
The election for general-secretary of the NUT takes place soon and the outcome could be an important factor in determining whether or not action escalates.
However, experience tells us that, in practice, a yawning gap divides what is said at teachers' conferences and what actually happens.
Nonetheless, ministers would be unwise to forget the strength of anger and opposition to performance-pay and, in particular, the link with pupils' results. For, as we approach Labour's mid-term, the Government knows it still has much to do to reach its heavily publicised targets on standards and teacher recruitment.
Industrial action, or any further damage to teachers' morale, would jeopardise those targets.
Last year's fall in the national results for 11-year-olds in mathematics was one warning of the mountain the Government must climb to reach the targets on which Education Secretary David Blunkett has staked his personal reputation. As for the Teacher Training Agency's targets on recruitment, many already look to be way beyond reach. Industrial action is not usually an effective recruiting sergeant.
With so many important battles still to be won, why risk opening up the equivalent of an eastern front on pay?
The mood of the teachers' conferences suggested they are prepared for a long campaign with all the sapping power of a Russian winter. This is not to say the Government has to admit it is wrong to want to link pay to pupils' performance.
It can still keep that as a long-term objective for a second term in office. Ministers could stick to their principles on pay, but trim their tactics.
They can even do so and save face. As Estelle Morris, the school standards minister, remarked: to change the plans now would not amount to a "concession" as the Green Paper was only a set of proposals for consultation.
When the Government sets out its response to the consultation towards the end of this month, ministers could simply say they listened and acted accordingly. One way forward would be to insist on the link between pay and appraisal, but to postpone indefinitely any link with pupils' results.
The NUT leadership very nearly persuaded its membership to support performance-pay linked to professional competencies. To get that in place would be a big enough step for now. At present, though, there is no sign at all that the Government will change tactics. Privately ministers believe that they already have support for the changes from around one-third of teachers. They regard that as a good base on which to build.
They are also determined in their belief that a link with pupil performance is fundamental to pay reforms.
As one adviser put it, somewhat bluntly; "If teachers don't make a difference in the classroom then what's the point of having them?" If ministers are wary of being seen to be caving in to union pressure, then they can cite others in evidence of a more tactical approach.
The Confederation of British Industry, in its response to the Green Paper, regrets that the debate over performance management has been "dominated by disputes over pay - it is necessary to move away from this type of confrontation and for all parties to begin to engage positively".
The CBI shares the Government's view that pay is important in raising standards performance.
At the same time, it sees no reason why the link with cash should not be delayed until the new system of performance management has "bedded down".
Politics is the art of compromise and some battles are more likely to be won by stealth than by full-frontal attack. Ministers might be well-advised to turn to their military histories before charging into battle with the unions over performance-related pay.
Mike Baker is the BBC's education correspondent