Megan Margulies is a writer, wife and mother.

A man dressed as Captain America engages in a snowball fight in Washington DC. EPA/MICHAEL REYNOLDS

Amid the masses of strangers gathered to protest at the Boston Women’s March, I spotted something familiar: that shield — red, white and blue — a simple design that holds the weight of so much conviction. Captain America’s iconic getup caught my eye, not only because of the principles it stands for but because he reminds me of another hero of mine.On Dec. 20, 1940, a year into World War II, my grandfather Joe Simon and Jack Kirby, both sons of Jewish immigrants, released the first issue of “Captain America.” The cover featured Cap slugging Adolf Hitler . Because the United States didn’t enter the war until late 1941, a full year later, Captain America seemed to embody the American spirit more than the actions of the American government.

As Cap socked the Führer, many rejoiced, but members of the German American Bund, an American pro-Nazi organization, were disgusted. Jack and my grandfather were soon inundated with hate mail and threatening phone calls, all with the same theme: “Death to the Jews.” As the threats continued, Timely Comics employees became nervous about leaving their building in New York. Then my grandfather took a call from Mayor Fiorello La Guardia, who promised to send police officers to protect them. “I was incredulous as I picked up the phone, but there was no mistaking the shrill voice,” my grandfather recalled in his book “The Comic Book Makers.” “ ‘You boys over there are doing a good job,’ the voice squeaked, ‘The City of New York will see that no harm will come to you.’ ”

I first visited my grandfather’s apartment when I was three days old. I was born in a hospital only a couple of blocks away, and my parents decided the first order of business was to introduce him to his first grandchild. Once I was able to talk, I called him Daddy Joe, a nickname that stuck with each following grandchild. As a teenager, I would hop on the subway to his studio apartment on weekends, escaping adolescent arguments and my family’s crowded apartment 20 blocks north. He always took me in, swiveling his ratty leather reclining chair to face me and greet me with a smile. He let me order greasy takeout and always kept his hallway closet stocked with soda. But more important, he offered me the solace of a quiet, turmoil-free place.

“Your mother loves you very much,” he said once during one of my many escapes. I grunted a teenage acknowledgment from the drawing table that held scraps of paper, ink stains and my half-eaten dinner. I knew he was right, of course, and he’d detected my uneasiness about my fights with her. But he didn’t push anything more than affirmation, and we settled into a routine: He would watch his football game, and I would dabble with his colored pencils. Captain America watched us from the walls.

For years, Captain America simply represented those evenings to me. He came to symbolize the immense love I had for my grandfather and, with that love, a kind of selfish chokehold on the character. More than once I approached a stranger wearing a Cap T-shirt and asked if they knew who created the superhero gracing their chest. It was an attempt, especially after his death, to shout his name far and wide, but also a childish statement: He’s mine. A part of me feared that by sharing my grandfather’s creation, our bond and the love that we had would be diluted. Cap was mine because Daddy Joe was mine.

Yet as I stood among thousands at the Boston Women’s March on Jan. 21, the personal suddenly felt global: More than five years after his death, my grandfather and his creation seemed newly meaningful. In life, my grandfather stood up for justice and taught me about compassion and understanding. Captain America contains all of that for me on a personal level, but now, in this time of turmoil for America, it’s clear that Cap represents something much larger, something we need as a nation.

Late last month, the Jewish Community Relations Council released a statement in response to President Trump’s executive order on immigration, saying that “these actions — which are causing anxiety, pain and anguish throughout immigrant communities and our nation — are unjust. We stand together on the side of empathy and religious tolerance and we urge the administration to open the gates of compassion to those seeking safety, regardless of their faith or country of origin.”

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While the daughters and sons of Jewish immigrants reject the travel ban, Cap’s only tool, that shield, is popping up in memes, on protest posters and on T-shirts. Created to defend America’s indestructible values, it is again serving as a tool to fight all that threatens our Constitution and our national decency. More than 75 years after his inception, Captain America, born to fight fascism and hatred, is being called into action once more, this time to defend American principles on our own soil. We need him. And I finally feel ready to share him.

Over the past few months I have loosened my selfish grip on that iconic shield, which is why I want to share it with you now. If it can offer someone solace, I will always be happy to share. More beautiful than the bold colors and sweeping perspective of that first comic book cover is this symbol of strength — a companion to our convictions about what is good and fair. Although Captain America can’t leap off the page and rescue those who feel the world has been turned upside down, he is powerful in his ability to offer an anchor of hope and an embodiment of our ideals, no matter your politics.

I framed the last postcard my grandfather sent me before he died: the face of Captain America painted on the front, his shield taking up half the small space. I photocopied the back of the postcard and framed it as well, placing them side by side on a bookshelf in my living room. “To lovely Megan — from the Captain and Joe Simon. Love you.”

That one sentence, scrawled in his boxy, cartoonist handwriting, serves as a reminder that I will always have two superheroes watching over me, and at least one to share with those who need him most.