How did the publication feat of Einstein's four 1905 Annus Mirabilis papers get through peer review?

Question

Einstein's early career is well-known for the lack of success he had applying for assistant lecturer positions with universities; he could not get a position, and he ended up working in a Bern patent office, in large part because his academic record didn't garner attention or respect from those in hiring positions.

Yet in 1905, Einstein's "Annus Mirabilis," he published 4 separate papers in the peer-reviewed Annalen der Physik (Annals of Physics)

• On the photoelectric effect: received March 18 and published June 9
• On Brownian motion: received May 11 and published July 18
• On special relativity: received June 30 and published Sept. 26
• On mass-energy equivalence: received Sept. 27 and published Nov. 21

It shocks me that someone with no active academic credentials or track record was able to publish four times in one year in such a prestigious journal. I have difficulty imagining the same thing happening today. While reviewers are supposed to review the work in and of itself, I'm sure there's some bias towards academic credentials and standing in the field; Einstein's papers were published regardless. Even if the reviewers were blinded to paper author, getting beyond the review to actual publication (four times!) seems a challenge. To me, this publication feat is nearly as impressive as the papers' subject matter.

QUESTION 1A: Has there been any research/writing on the reviewers of these papers, their initial thoughts, and the process that led to publication? I would think Annalen der Physik might still have records of the review process. Apparently, the reviewers looked beyond Einstein's lack of credentials and radical thinking. That's magnificent, yet surprising.

QUESTION 1B: Were the papers so cogent that non-publication was inconceivable? The papers were groundbreaking proposals for the most part (Lorentz and Poincare had done work leading towards special relativity), and the mass-energy equivalence paper had no empirical (atomic bomb) evidence to substantiate it.

Answer 1

I am afraid, you are overprojecting the power and the glory of peer review. Although some instances can be cited as early as 17th century, it only became what it is today with the triumph of publish or perish in mid 20th, see How did "publish or perish" become the scientific priority rule?

Concerning Einstein's papers specifically see Hate the peer-review process? Einstein did too:

"Academic review process was different in Einstein’s time. In his brilliant career, the only time his work was subjected to blind peer review – the authors don’t know the reviewers and vice versa – he showed contempt for what is now the gold standard of science.

[...] For instance, the Annalen der Physik, in which Einstein published his four famous papers in 1905, did not subject those papers to the same review process. The journal had a remarkably high acceptance rate (of about 90-95%). The identifiable editors were making the final decisions about what to publish. It is the storied editor Max Planck who described his editorial philosophy as: To shun much more the reproach of having suppressed strange opinions than that of having been too gentle in evaluating them."

The "only time" was in 1935 in the US, which was ahead of the curve on peer review. When Physical Review tried to peer review an Einstein-Rosen paper on gravitational waves it got the following response from Einstein:

"We (Mr. Rosen and I) had sent you our manuscript for publication and had not authorised you to show it to specialists before it is printed. I see no reason to address the – in any case erroneous – comments of your anonymous expert. On the basis of this incident I prefer to publish the paper elsewhere."