After I composed this, I found that Rav Samet had written largely the same thing (with the same sources!)—שלח—המעפילים. Also see רב דוד לבנון's article in yeshiva.org.il, המעפילים for a brilliant connection between the מעפילים, בנות צלופחד and בי יהודה בן בתירא.
After ה׳ condemns בני ישראל to 40 years in the wilderness, some of them try to enter the land anyway:
And Moshe’s description in ספר דברים makes it clear that ה׳ told them not to go:
In modern Hebrew, עפל means to climb, but that is redundant here (ויעפלו לעלות). In other contexts, it means “swollen, puffed up” (in the תוכחה, עפלים is generally translated “tumors”). Rashi translates it metaphorically, as in חבקוק:
So Artscroll translates “they defiantly ascended”. I would translate it as חוצפא: ”they went up with chutzpah“; “they had some nerve going up after ה׳ told them not to”. And these people are known as the מעפילים, ”the chutzpadik ones“.
The Netsiv puts a positive spin on their actions.
They are willing to fight, even give up their lives, to fulfill ה׳'s command (נלחמנו ככל אשר צונו ה׳ אלקינו), even to the point of מסירת נפש, but without תשובה it can’t succeed:
They had such love of the land (exactly the opposite of the people who cried after the report of the spies) that they would rather die in ארץ ישראל than live in חוץ לארץ.
And the term מעפילים is used in contemporary times to refer to the illegal immigration—עלייה ב׳—immediately before the establishment of the state of Israel:
They had the “chutzpah” to defy the law (not of G-d’s but of the British, though we will discuss that below) and risk their lives, out of a love of ארץ ישראל.
And that chutzpah, to literally defy G-d, is not always bad:
Rav Tzadok miLublin applied this idea to the מעפילים. The gemara talks about how, in the time leading up to אחרית הימים, chutzpah will spread:
That is usually understood as one of the negative aspects of the “birth pangs of Mashiach”:
But Rav Tzadok looks at it as a positive:
As we approach the גאולה, there will be מעפילים, those who “defiantly ascend”, against all the rules, even against the word of G-d:
And they will go without ארון ברית ה׳ ומשה, in the ultimate חוצפא יסגא. And they will succeed: והיא לא תצלח. היא ולא אחרת, שיש זמן אחר שמצליח והוא זמננו.
And I am Zionist enough to say that this is what the founding of מדינת ישראל was, and that ה׳ looked at our chutzpah and smiled: