Schools in Calderdale excluded dozens of pupils for assaulting adults last year, figures reveal.
Teaching unions say government cuts to education funding have left schools less able to help children with challenging behaviour before it escalates.
Department for Education data shows that Calderdale's schools excluded students 93 times for assaulting adults in 2017-18, although this was a drop from 98 the previous year.
Of these, 89 were temporary exclusions and four were permanent.
Physical assault can mean a pupil wounding, obstructing and jostling, or behaving violently towards an adult.
The figures include assaults by children at state-funded primary, secondary and special schools in the area.
Dr Mary Bousted, joint general secretary of the National Education Union, said teachers often cite pupil behaviour as a reason why they walk away from the profession.
She added: “All schools should have a policy for dealing with violent incidents, and a pupil behaviour policy where teachers feel genuinely supported by school management.
“Cuts to school and local authority budgets, however, mean many support services such as behavioural specialists, who used to help in schools, have gone."
Calderdale schools excluded pupils 1,369 times in 2017-18 – 43 of these were permanent.
This was a 25 per cent drop on the previous year, when they handed out 1,836.
The drop in exclusions in Calderdale bucks the trend across England, where the total rose by seven per cent to 419,000.
General secretary of the Association of School and College Leaders, Geoff Barton, said school leaders have a duty to keep their staff and pupils safe.
He added: “Schools are working hard to avoid having to exclude pupils, but the Government must do more to back them up, with an improved level of funding for education and investment in local services, which provide support to vulnerable families and children.”
Exclusions have become a hot topic after fears some schools are off-rolling, through which pupils are removed from their register without a permanent exclusion, possibly to improve average exam results.
A government review published earlier this year vowed to make schools more accountable for pupils they remove.
A DfE spokesperson said schools have a duty to protect pupils and staff, and added that the department will continue to back leaders in using permanent exclusion as a last resort.
They added: “There is no right number of exclusions, and although exclusion rates remain lower than 10 years ago, we have been clear that exclusion from school should not mean exclusion from education.
“Following the Timpson Review, we are consulting on how to make schools more accountable for the students they exclude, working with Ofsted to clamp down on off-rolling, and calling on local areas to explain or change trends in exclusions for certain groups of children.”