I think so
Yes to form defensive coalitions. Not to actually choose in most cases to initiate a war. That's like saying if a homeowner beats up a burgular who breaks into his house and attacks him when discovered is guilty of assault. Britain definitely didn't want war in 1914 but many recognised that if war came and our allies were attacked and defeated quickly Britain would be very exposed. Fortunately the invasion of Belgium made the issue clear for the vast bulk of the population in the UK.
England do not have allies,only affairs.
If WW1 start 10 years later,when Russian Empire would be much stronger,then London would support germans.And i do not blame them - their politics of always beating stronger country in Europe was logical.
Back to topic - i had 3 candidates:
1.Machomet - kill him before he start his religion.We would have normal Middle East ruled by cyvilized persians.
2.Dzyngis Khan - his empire falled after few generations,but he made one thing lasting - he murdered russians ,and his descendents turned them into muscovites.Could you imagine world with normal Russia?
3.Frederick the great thief - kill him in 1756,just after he started war.Prussia destroyed as state,and - we have normal germans,not genocidal idiots.
Althought,if i kill Machomet,at least Freferick would probably never be born.