The Prime Minister has warned the Army's newest officer recruits that challenges posed by terrorist groups and changing alliances have made the world more complex than ever before.
Speaking as the Queen's representative at the Sovereign's Parade at Sandhurst Academy, Theresa May referenced Khalid Masood's deadly attack in Westminster last month.
She also commended former Sandhurst graduate Captain Michael Crofts for tending to the wounded as the day unfolded.
Mrs May said she wanted Britain to build a "new and deep special partnership" with the European Union as the UK enters into negotiations to leave the bloc following the EU referendum last June.
"The world into which you all now enter is also very different from that which confronted many of your predecessors. The threats we face today are more complex than ever before. And the missions that you will be asked to undertake will be similarly complex."
Theresa May witnessed the ceremony as the Sovereign's Representative while the Queen attended Maundy Thursday celebrations in Leicester.
The Prime Minister inspected the 587 officer cadets while the military band played the Star Wars theme
The event marks only the third year when male and female officers have passed out together at the academy, having previously had separate parades for each sex.
Among the present officer cadets the Prime Minister mentioned as noteworthy graduates was the Prime Minister of Bahrain, Sheikh Khalifah's daughter - the first ever Bahrani woman to gratuate from the Academy.
She also heralded the commission of the first ever female officer to serve in the Royal Tank regiment - a direct result of the decision to enable women to serve in the combat arms and something of which Mrs May said the army could be "incredibly proud".
Women cadets have been on exercise, training and living with their male counterparts since January 2015 in a move designed reflect the modern day-to-day workings of the Army.
Mrs May went on to praise the dedication of the armed forces as a whole and said: "Nothing fills me with more admiration and gratitude than the exceptional commitment of our armed forces - and their families, who are such a critical part of that sacrifice and service to our country.
"As Prime Minister I want to say very clearly on behalf of the whole country - we will always stand proudly behind you."