Following the interrogation of Arnim Zola, it was learned that HYDRA was planning an attack on the United States of America. Carter attended a briefing run by Colonel Chester Phillips and learned about Red Skull's plans with his Tesseract technology while they discussed their plan to bring an end to HYDRA and Red Skull himself. Along with Howard Stark and the remaining members of the Howling Commandos, crafted a plan in which Steve Rogers break through their defenses.
Once Rogers attacked HYDRA's last base of operations, allowing himself to be captured in order to distract Red Skull and allowed the United States Army time to attack the base. While Phillips had the called to enter in the base, Carter followed along with the assault force, as the HYDRA soldiers began to fire with their Assault Weapons. While the many soldiers were killed one by one with each fire power, Carter managed survive and broke into HYDRA's base of operation with Phillips killing one of them upfront.
Comic book version of Peggy Carter.
"That was a difficult winter. A blizzard had trapped half our battalion behind the German line. Steve... Captain Rogers, he fought his way through a HYDRA blockade that had pinned our allies down for months. He saved over a thousand men, including the man who would... who would become my husband as it turned out."
Growing up in Los Angeles in the 70s/80s we visited Disneyland on a regular basis and often after school, before "Annual Passes".